Orexin-B-SAP References

Orexin-B-SAP (Cat. #IT-20)

80 entries found for : it-20

A century searching for the neurons necessary for wakefulness

Grady FS, Boes AD, Geerling JC (2022) A century searching for the neurons necessary for wakefulness. Front Neurosci 16:930514. doi: 10.3389/fnins.2022.930514

Objective: This review article attempts to summarize research that has investigated the neurons necessary for wakefulness.

Summary: The authors summarize animal experiments and research performed in different brain regions to further understand wakefulness. Several saporin conjugates are discussed.

Usage: Lesions of the basal forebrain were done by injecting a 0.1% solution of either 192-IgG-SAP or Orexin-SAP at four different sites (Fuller et al. and Geraschenko et al.); Intraventricular injection of Anti-DBH-SAP (Gompf et al.); Bilateral injections of 192-IgG-SAP (Kaur et al.).

Related Products: Orexin-B-SAP (Cat. #IT-20)

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Expert Opinion: Managing sleep disturbances in people with epilepsy

Nobili L, Beniczky S, Eriksson SH, Romigi A, Ryvlin P, Toledo M, Rosenzweig I (2021) Expert Opinion: Managing sleep disturbances in people with epilepsy. Epilepsy Behav 124:108341. doi: 10.1016/j.yebeh.2021.108341

Summary: The authors suggest that the dose and timing of antiepileptic medications and other co-medications should always be optimized in order to improve nocturnal sleep and avoid daytime sedation.

See: Hasegawa H et al. The subcortical belly of sleep: New possibilities in neuromodulation of basal ganglia?. Sleep Med Rev 52:101317, 2020.

Related Products: Orexin-B-SAP (Cat. #IT-20)

Neural circuitry underlying REM sleep: A review of the literature and current concepts

Wang YQ, Liu WY, Li L, Qu WM, Huang ZL (2021) Neural circuitry underlying REM sleep: A review of the literature and current concepts. Prog Neurobiol 204:102106. doi: 10.1016/j.pneurobio.2021.102106

Summary: To investigate the role of the LC in sleep the authors injected 0.3 µl of 192-Saporin (Cat. IT-01) or anti-DBH-SAP (Cat. #IT-03) at 1 µg/µl. They also used 0.3 µl of orexin-SAP (Cat. #IT-20) at either 90 ng/µl or 60 ng/µl in a separate group of animals. The results indicate that orexin innervation to the pons plays a role in arousal from sleep.

Related Products: Orexin-B-SAP (Cat. #IT-20), 192-IgG-SAP (Cat. #IT-01), Anti-DBH-SAP (Cat. #IT-03)

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The effects of orexin-A and orexin receptors on anxiety- and depression-related behaviors in a male rat model of post-traumatic stress disorder

Han D, Shi Y, Han F (2022) The effects of orexin-A and orexin receptors on anxiety- and depression-related behaviors in a male rat model of post-traumatic stress disorder. J Comp Neurol 530(3):592-606. doi: 10.1002/cne.25231

Objective: To determine the role of the orexin system in mediating anxiety- and depression-related behaviors in PTSD.

Summary: Intracerebroventricular administration of orexin-A alleviated behavioral changes in a PTSD rat model and partly restored the increased levels of OX1R in the medial prefrontal cortex (mPFC). These results suggest that the orexin system plays a role in the anxiety- and depression-related symptoms observed in PTSD.

See: Kaur S et al. Hypocretin-2 saporin lesions of the ventrolateral periaquaductal gray (vlPAG) increase REM sleep in hypocretin knockout mice. PLoS One 4:e6346, 2009.

Related Products: Orexin-B-SAP (Cat. #IT-20)

Effects of propofol on sleep architecture and sleep-wake systems in rats

Yue XF, Wang AZ, Hou YP, Fan K (2021) Effects of propofol on sleep architecture and sleep-wake systems in rats. Behav Brain Res 411:113380. doi: 10.1016/j.bbr.2021.113380

Objective: To characterize the effects of propofol on the profile of sleep–wake states and cortical electroencephalogram (EEG) power spectral density in rats following intraperitoneal injection.

Summary: The high dose of propofol produced high-quality sleep by increasing SWS2, whereas the medium dose produced fragmented and low-quality sleep by disrupting the continuity of wakefulness.

Usage: Bilateral injection of Orexin-SAP (92 and 184 ng/ml, 0.25 ml in the ventral tegmental area and 0.5 ml in the substantia nigra) of rats induced insomnia, as well as hyperactivity and stereotypic movements

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The medial septum as a potential target for treating brain disorders associated with oscillopathies

Takeuchi Y, Nagy AJ, Barcsai L, Li Q, Ohsawa M, Mizuseki K, Berényi A (2021) The medial septum as a potential target for treating brain disorders associated with oscillopathies. Front Neural Circuits 15:701080. doi: 10.3389/fncir.2021.701080

Summary: The medial septum (MS) may be a potential target for treating neurological and psychiatric disorders with abnormal oscillations (oscillopathies) to restore healthy patterns or erase undesired ones. The time-targeted strategy for the MS stimulation may provide an effective way of treating multiple disorders.

Usage: 192-IgG-SAP. The MS cholinergic neurons along with theta oscillations are known to be essential for memory because selective lesion of the cholinergic neurons resulted in spatial memory impairments (150 ng; Easton et al., 2011) (5.04 μg icv; Jeong et al., 2014). Orexin-SAP. The enhanced gamma oscillations and altered PPI and auditory gating created by psychoactive drugs in rats were mediated by GABAergic neurons in the MS because they were abolished by ablation of these neurons by Orexin-SAP (140 ng total bilateral; Ma et al., 2012). mu p75-SAP. Anxious environment-induced type 2 theta oscillation and associated anxiety were shown to be dependent on the MS cholinergic neurons because lesion of MS cholinergic neurons reduced them (0.65 or 1.3 µg, bilateral; Nag et al., 2009).

Related Products: 192-IgG-SAP (Cat. #IT-01), mu p75-SAP (Cat. #IT-16), Orexin-B-SAP (Cat. #IT-20)

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Medial parabrachial nucleus is essential in controlling wakefulness in rats

Xu Q, Wang DR, Dong H, Chen L, Lu J, Lazarus M, Cherasse Y, Chen GH, Qu WM, Huang ZL (2021) Medial parabrachial nucleus is essential in controlling wakefulness in rats. Front Neurosci 15:645877. doi: 10.3389/fnins.2021.645877

Summary: Lesions of the LC with 192-IgG-SAP have no significant effect on wakefulness in rats (Blanco-Centurion et al.). Only the Orexin-SAP lesion involved in the MPB region resulted in the dramatic decrease of wakefulness in rats (Fuller et al.).

Related Products: 192-IgG-SAP (Cat. #IT-01), Orexin-B-SAP (Cat. #IT-20)

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A common neuronal mechanism of hypertension and sleep disturbances in spontaneously hypertensive rats: Role of orexinergic neurons.

Cui S-Y, Huang Y-L, Cui X-Y, Zhao H-L, Hu X, Liu Y-T, Qin Y, Kurban N, Zhang Y-H (2020) A common neuronal mechanism of hypertension and sleep disturbances in spontaneously hypertensive rats: Role of orexinergic neurons. Prog Neuropsychopharmacol Biol Psychiatry 100:109902. doi: 10.1016/j.pnpbp.2020.109902

Objective: To investigate dynamic changes in sleep patterns during the development of hypertension.

Summary: Although the correlation between sleep disturbances and hypertension is very complex, common mechanisms may underlie these comorbidities.

Usage: Orexin-B-SAP (HCRT2-SAP) was administered in two injections/side (100 and 200 ng/0.5 μl/injection).

Related Products: Orexin-B-SAP (Cat. #IT-20)

The subcortical belly of sleep: New possibilities in neuromodulation of basal ganglia?

Hasegawa H, Selway R, Gnoni V, Beniczky S, Williams SCR, Kryger M, Ferini-Strambi L, Goadsby P, Leschziner GD, Ashkan K, Rosenzweig I (2020) The subcortical belly of sleep: New possibilities in neuromodulation of basal ganglia?. Sleep Med Rev 52:101317. doi: 10.1016/j.smrv.2020.101317

Summary: Complete BF lesion with OX-SAP leads to coma-like state and flat EEG, reduced Fos in cerebral cortex (but high Fos in brainstem, thalamus, hypothalamus) selective (cholinergic or non-cholinergic) lesion does not have this effect.

Usage: Lesions of the basal forebrain were done by injecting a 0.1% solution of Orexin-SAP at four different sites.

See: Fuller P et al. Reassessment of the structural basis of the ascending arousal system. J Comp Neurol 519(5):933-956, 2011.

Related Products: Orexin-B-SAP (Cat. #IT-20)

SUVN-G3031, histamine H3 receptor inverse agonist preclinical evaluation for the treatment of excessive daytime sleepiness in narcolepsy

Bhyrapuneni G, Benade V, Daripelli S, Kamuju V, Shinde A, Abraham R, Nirogi R, Jasti V (2019) SUVN-G3031, histamine H3 receptor inverse agonist preclinical evaluation for the treatment of excessive daytime sleepiness in narcolepsy. Neuroscience 2019 Abstracts 502.07. Society for Neuroscience, Chicago, IL.

Summary: Numerous studies have demonstrated that brain histamine plays a crucial role in maintenance of wakefulness, attention, learning and other cognitive processes. SUVN-G3031, a potent histamine H3 receptor inverse agonist is being developed for the treatment of narcolepsy and other sleep related disorders. SUVN-G3031 is one of the lead molecules with hKi of 8.7 nM and has more than 100 fold selectivity against the related GPCRs. SUVN-G3031 exhibited desired pharmacokinetic properties and brain penetration. SUVN-G3031 blocked R-α-methylhistamine induced water intake and increased tele-methylhistamine levels in brain and cerebrospinal fluid. In the present study, SUVN-G3031 was evaluated in brain microdialysis and rodent models of electroencephalography (EEG). SUVN-G3031 was evaluated in brain microdialysis for evaluation of neurotransmitters like acetylcholine, histamine, dopamine and norepinephrine in male Wistar rats. EEG was used to evaluate the effects on sleep/ wake profile in rats and mice.A single oral administration of SUVN-G3031 produced significant increase in acetylcholine, histamine, dopamine and norepinephrine levels in the cortex. SUVN-G3031 produced no change in the dopamine levels of striatum and nucleus accumbens indicating that SUVN-G3031 may not have addiction liabilities. Narcoleptic-like sleep behavior was observed in rats injected with hypocretin-2-saporin in lateral hypothalamus. SUVN-G3031 produced significant increase in wakefulness with concomitant decrease in rapid eye movement (REM) sleep in these animals. These results are in agreement with EEG studies carried out in healthy male Wistar rats. Results from current studies provide strong evidence for the potential of SUVN-G3031 in the treatment of excessive daytime sleepiness associated with narcolepsy. First in human, Phase 1 studies for SUVN-G3031 are completed under US IND and SUVN-G3031 has shown desirable pharmacokinetic profile with safety and tolerability in healthy human volunteers. Phase 2 study for the treatment of excessive daytime sleepiness associated with narcolepsy is currently ongoing in USA.

Related Products: Orexin-B-SAP (Cat. #IT-20)

Cannabidiol partially blocks the excessive sleepiness in hypocretindeficient rats: Preliminary data.

Murillo-Rodríguez E, Millán-Aldaco D, Palomero-Rivero M, Morales-Lara D, Mechoulam R, Drucker-Colín R (2019) Cannabidiol partially blocks the excessive sleepiness in hypocretindeficient rats: Preliminary data. CNS Neurol Disord Drug Targets 18(9):705-712. doi: 10.2174/1871527318666191021143300

Objective: To determine whether the systemic injection of CBD (5 mg/kg, i.p.) would block the excessive sleepiness in a narcoleptic model.

Summary: Preliminary findings suggest that CBD might prevent sleepiness in narcolepsy.

Usage: Orexin-SAP (490 ng/0.5 μL, n= 10) was bilaterally injected into the LH of rats to eliminate HCRT leading to the establishment of narcoleptic-like behavior.

Related Products: Orexin-B-SAP (Cat. #IT-20)

0054 SUVN-G3031, a histamine H3 receptor inverse agonist produces wake promoting effect in orexin-2-saporin lesioned rats.

Benade V, Daripelli S, Tirumalasetty C, Subramanian R, Petlu S, Badange R, Nirogi R (2019) 0054 SUVN-G3031, a histamine H3 receptor inverse agonist produces wake promoting effect in orexin-2-saporin lesioned rats. Sleep 42(Supplement_1):A22-A23. doi: 10.1093/sleep/zsz067.053

Summary: Rats lesioned with Orexin-SAP in lateral hypothalamus produced narcoleptic-like behavior.

Related Products: Orexin-B-SAP (Cat. #IT-20)

Discovery and development of N-[4-(1-Cyclobutylpiperidin-4-yloxy)phenyl]-2-(morpholin-4-yl)acetamide Dihydrochloride (SUVN-G3031): A novel, potent, selective, and orally active histamine H3 receptor inverse agonist with robust wake-promoting activity.

Nirogi R, Shinde A, Mohammed AR, Badange RK, Reballi V, Bandyala TR, Saraf SK, Bojja K, Manchineella S, Achanta PK, Kandukuri KK, Subramanian R, Benade V, Palacharla RC, Jayarajan P, Pandey S, Jasti V (2019) Discovery and development of N-[4-(1-Cyclobutylpiperidin-4-yloxy)phenyl]-2-(morpholin-4-yl)acetamide Dihydrochloride (SUVN-G3031): A novel, potent, selective, and orally active histamine H3 receptor inverse agonist with robust wake-promoting activity. J Med Chem 62(3):1203-1217. doi: 10.1021/acs.jmedchem.8b01280

Objective: To discover and develop a therapeutic for human sleep disorders.

Summary: Histamine H3 Receptor Inverse Agonist demonstrated high receptor occupancy and marked wake promoting effects with decreased REM sleep in Orexin-B-SAP lesioned rats. This study supports its potential therapeutic utility in treating human sleep disorders.

Usage: Injections (490 ng/0.8 μl) were made bilaterally to the lateral hypothalamus.

Related Products: Orexin-B-SAP (Cat. #IT-20)

SUVN-G3031, H3 receptor inverse agonist produces wake promoting activity in rats with hypocretin-2-saporin lesions of the lateral hypothalamus

Daripelli S, Bhayrapuneni G, Tirumalesetty C, Benade V, Subramanian R, Petlu S, Praveena N, Jayarajan P, Shinde A, Badange R, Bhatta V, Nirogi R (2018) SUVN-G3031, H3 receptor inverse agonist produces wake promoting activity in rats with hypocretin-2-saporin lesions of the lateral hypothalamus. Neuroscience 2018 Abstracts 679.23 / VV4. Society for Neuroscience, San Diego, CA.

Summary: Numerous studies have demonstrated that brain histamine plays a crucial role in maintenance of wakefulness, attention, learning and other cognitive processes. SUVN-G3031, a potent H3 receptor inverse agonist is being developed for the treatment of narcolepsy and other sleep related disorders. SUVN-G3031 is one of the lead molecules with hKi of 8.7 nM and has more than 100 fold selectivity against the related GPCRs. SUVN-G3031 exhibited desired pharmacokinetic properties and brain penetration. SUVN-G3031 blocked R-α-methylhistamine induced water intake and increased tele-methylhistamine levels in brain and cerebrospinal fluid. A single oral administration of SUVN-G3031 produced significant increase in acetylcholine, histamine, dopamine and norepinephrine levels in the cortex. SUVN-G3031 produced wake promoting activity in male Wistar rats. In the present study, effects of SUVN-G3031 on sleep/ wake profile were evaluated in rats with lateral hypothalamic lesion using neurotoxin hypocretin-2-saporin. Narcoleptic-like sleep behavior was observed in rats injected with hypocretin-2-saporin in lateral hypothalamus. SUVN-G3031 produced significant increase in wakefulness with concomitant decrease in rapid eye movement (REM) sleep in these animals. These results are in agreement with electroencephalography (EEG) studies carried out in healthy male Wistar rats. Results from the current study and the neurotransmitter modulations produced by SUVN-G3031 provide a strong basis for the potential of SUVN-G3031 in treatment of sleep related disorders. First in human, Phase 1 studies for SUVN-G3031 are completed underUS IND and SUVN-G3031 has shown desirable pharmacokinetic profile with safety and tolerability in healthy human volunteers. Phase 2 study for narcolepsy is currently being planned.

Related Products: Orexin-B-SAP (Cat. #IT-20)

Orexinergic neurons are involved in the chemosensory control of breathing during the dark phase in a Parkinson’s disease model.

Oliveira LM, Falquetto B, Moreira TS, Takakura AC (2018) Orexinergic neurons are involved in the chemosensory control of breathing during the dark phase in a Parkinson's disease model. Exp Neurol 309:107-118. doi: 10.1016/j.expneurol.2018.08.004

Objective: To determine the involvement of orexin cells from the lateral hypothalamus/perifornical area (LH/PeF) on breathing.

Summary: The degeneration of orexinergic neurons in this model of PD can be related to impaired chemoreceptor function in the dark phase.

Usage: For lesions of LH/PeF, two injections of Orexin-B-SAP or Rabbit IgG-SAP (100 ng/μl) were made into the lateral hypothalamus / perifornical area (LH/PeF).

Related Products: Orexin-B-SAP (Cat. #IT-20), Rabbit IgG-SAP (Cat. #IT-35)

Depletion of hypocretin/orexin neurons increases cell proliferation in the adult subventricular zone

Arias-Carrion O, Ortega-Robles E, de Celis-Alonso B, Palasz A, Mendez-Rojas MA, Salas-Pacheco J, Murillo-Rodriguez E (2018) Depletion of hypocretin/orexin neurons increases cell proliferation in the adult subventricular zone. CNS Neurol Disord Drug Targets 17:106-112. doi: 10.2174/1871527317666180314115623

Objective: To establish the relationship between the depletion of orexin neurons and the number of proliferating cells in the subventricular zone.

Summary: The adult subventricular zone is affected by orexinergic signaling, the functional implication of which must be further elucidated.

Usage: 90 ng of Orexin-SAP or pyrogen-free saline was stereotaxically injected into the lateral hypothalamus (3.2 caudal, 1.7 lateral to bregma, 8.1 ventral to the skull surface) of male Wistar rats.

Related Products: Orexin-B-SAP (Cat. #IT-20)

Role of orexinergic neurons in the chemosensory control of breathing in a Parkinson’s disease model

Falquetto B, Oliveira LM, Moreira TS, Takakura AC (2017) Role of orexinergic neurons in the chemosensory control of breathing in a Parkinson’s disease model. Neuroscience 2017 Abstracts 779.08 / HH1. Society for Neuroscience, Washington, DC.

Summary: Parkinson´s disease (PD) is a neurodegenerative disorder characterized by progressive loss of dopaminergic neurons in the substantia nigra compacta (SNpc). Non-motor symptoms such as neuropsychiatric, sleep and breathing disorders are also observed in PD. Previous study has already demonstrated that in 6-hydroxydopamine (6-OHDA)-model of PD there is a reduction in the number of phox2b neurons in the retrotrapezoid nucleus (RTN) and a decrease in the respiratory response to hypercapnia. Here, we tested the involvement of orexin cells from lateral hypothalamus/perifornical area (LH/PeF) on breathing in this model of PD. 6-OHDA (24 µg/µl) injections into the striatum reduced the number of catecholaminergic (40 days: 128 ± 10 and 60 days: 116 ± 13 vs. vehicle: 938 ± 15 neurons) and orexin-B-ir neurons (40 days: 310 ± 9 and 60 days: 258 ± 15 vs. vehicle: 412 ± 13 neurons). The injection of anti-Orexin-B saporin into the LH/PeF produces a further reduction in the number of orexinergic neurons in PD animals (79 ± 8 vs. control: 427 ± 14 neurons). The respiratory frequency (fR) at rest and in response to hypercapnia (7% CO2) was assessed 60 days after bilateral 6-OHDA or vehicle injections into the striatum and anti-Orexin-B saporin or IgG saporin into the LH/PeF during sleep and wakefulness in the dark and light phases of the diurnal cycle. Sixty days after 6-OHDA, we observed a reduction of fR at rest during sleep in the light phase only in PD animals (56 ± 2 vs. control: 66 ± 2 bpm). During the dark phase, there is a reduction in fR response to hypercapnia in PD animals with depletion of orexinergic neurons during wakefulness (119 ± 6 vs. control: 152 ± 3 bpm) and sleep (128 ± 7 vs. control: 147 ± 5 bpm). Our data suggest that orexinergic neurons are important to restore chemoreceptor function in a rat model of PD during sleep and wakefulness in rats.

Related Products: Orexin-B-SAP (Cat. #IT-20)

ATS Poster of the Year Winner

Locus coeruleus noradrenergic innervation of the amygdala facilitates alerting-induced constriction of the rat tail artery.

Mohammed M, Kulasekara K, Ootsuka Y, Blessing W (2016) Locus coeruleus noradrenergic innervation of the amygdala facilitates alerting-induced constriction of the rat tail artery. Am J Physiol Regul Integr Comp Physiol 310:R1109-1119. doi: 10.1152/ajpregu.00058.2016

Summary: The researchers tested the hypothesis that release of noradrenaline within the amygdala is important for the occurrence of SCVARS (sympathetic cutaneous vasoconstrictor alerting responses). A long-shanked 5-μl glass micropipette calibrated in 100-nl steps, was filled with vehicle or Anti-DBH-SAP (Cat. #IT-03). Anti-DBH-SAP (5 μg in 250 nl) or vehicle was injected into the amygdala during ∼1 min, and the pipette was left in place for an additional The locus coeruleus has been implicated in many aspects of emotional arousal, so that functional inhibition of the extensive locus coeruleus-derived noradrenergic innervation of centers known to be important in emotional arousal, including the amygdala, is likely to contribute to the therapeutic actions of clonidine-like agents. The locus coeruleus also has major reciprocal connections with the orexin-synthesizing neurons in the hypothalamus, and rats with genetically lesioned orexin receptor neurons (alternatively, oen could lesion with Orexin-SAP, Cat. #IT-20) have reduced emotional arousal as reflected in reduced SCVAR responses to alerting stimuli.

Related Products: Anti-DBH-SAP (Cat. #IT-03), Orexin-B-SAP (Cat. #IT-20)

Locus coeruleus and tuberomammillary nuclei ablations attenuate hypocretin/orexin antagonist-mediated rem sleep.

Schwartz M, Nguyen A, Warrier D, Palmerston J, Thomas A, Morairty S, Neylan T, Kilduff T (2016) Locus coeruleus and tuberomammillary nuclei ablations attenuate hypocretin/orexin antagonist-mediated rem sleep. eNeuro 3:ENEURO.0018-0016.2016. doi: 10.1523/ENEURO.0018-16.2016

Summary: To examine the mechanism by which the Orexin 1r/Orexin 2r antagonist almorexant decreases wakefulness and increases NREM and REM sleep the authors utilized Anti-DBH-SAP (Cat. #IT-03) and Orexin-B-SAP (Cat. #IT-20). Rats received 3-μg injections of Anti-DBH-SAP into the LC, or bilateral 57-80 ng injections of Orexin-SAP into the TMN. Both conjugates attenuated the increased REM sleep seen upon administration of almorexant without altering almorexant-induced changes in NREM sleep.

Related Products: Anti-DBH-SAP (Cat. #IT-03), Orexin-B-SAP (Cat. #IT-20)

Orexin A activates hypoglossal motoneurons and enhances genioglossus muscle activity in rats.

Zhang G, Liu Z, Zhang B, Geng W, Song N, Zhou W, Cao Y, Li S, Huang Z, Shen L (2014) Orexin A activates hypoglossal motoneurons and enhances genioglossus muscle activity in rats. Br J Pharmacol 171:4233-4246. doi: 10.1111/bph.12784

Summary: Orexin neurons are restricted to the lateral hypothalamus (LH) and are involved in functions such as feeding behavior, energy homeostasis, sleep/wake cycles, and many others. Here the authors investigate orexin control of the genioglossus – the largest upper airway dilator muscle. Rats received bilateral 172 ng injections of orexin-SAP into the LH. Lesioned animals displayed a significant decrease in genioglossus muscle electromyograms, indicating that orexin neurons are vital to the control of this muscle.

Related Products: Orexin-B-SAP (Cat. #IT-20)

Armodafinil-induced wakefulness in animals with ventrolateral preoptic lesions.

Vetrivelan R, Saper C, Fuller P (2014) Armodafinil-induced wakefulness in animals with ventrolateral preoptic lesions. Nat Sci Sleep 6:57-63. doi: 10.2147/NSS.S53132

Summary: Excessive daytime sleepiness is often treated with modafinil. Armodafinil, the R-isomer of modafinil, has been introduced for clinical use, but little is known about the cellular pathway targeted by these drugs. The authors examined whether armodafinil inhibits the ventrolateral preoptic nucleus (VLPO). Rats received 200-ng injections of orexin-SAP into the VLPO, followed by administration of armodafinil. Lesioned animals displayed increased wakefulness similar to control animals, indicating that armodafinil and modafinil do not act along the VLPO neurons.

Related Products: Orexin-B-SAP (Cat. #IT-20)

Role of lateral hypothalamus in two aspects of attention in associative learning.

Wheeler D, Wan S, Miller A, Angeli N, Adileh B, Hu W, Holland P (2014) Role of lateral hypothalamus in two aspects of attention in associative learning. Eur J Neurosci 40:2359-2377. doi: 10.1111/ejn.12592

Summary: The lateral hypothalamic (LH) region contains both orexin and melanin-concentrating hormone (MCH) neurons. These neurons are unique to the LH but project throughout the brain. In this work the authors examined the role of the LH in specific attentional aspects of associative learning. Rats received unilateral 500 ng injections of orexin-SAP (IT-20) into the LH and were tested in several learning tasks. The lesioned animals displayed impaired behavior that was correlated to the loss of orexin but not MCH neurons.

Related Products: Orexin-B-SAP (Cat. #IT-20)

Effects of hypocretin/orexin cell transplantation on narcoleptic-like sleep behavior in rats.

Arias-Carrión O, Murillo-Rodríguez E (2014) Effects of hypocretin/orexin cell transplantation on narcoleptic-like sleep behavior in rats. PLoS One 9:e95342. doi: 10.1371/journal.pone.0095342

Summary: In this work the authors examined the effect of orexin cell grafts into the lateral hypothalamus (LH) on narcoleptic-like sleep behavior. Rats received bilateral 490-ng injections of orexin-SAP* into the LH. 21 days post-lesion, the animals then received a graft consisting of dissociated cells from a 8-10 day old rat brain. The narcoleptic-like behavior was reduced in animals receiving the graft, indicating that restoration of some orexin levels may help resolve neurodegeneration.

Related Products: Orexin-B-SAP (Cat. #IT-20)

Physiology of the orexinergic/hypocretinergic system: a revisit in 2012.

Kukkonen JP (2013) Physiology of the orexinergic/hypocretinergic system: a revisit in 2012. Am J Physiol Cell Physiol 304(1):C2-32 . doi: 10.1152/ajpcell.00227.2012

Summary: This review updates an original review from a decade ago on the subject of orexins. These neuropeptides have been shown to be involved in sleep, wakefulness, appetite, metabolism, stress response, reward/addiction, and analgesia. This broad spectrum of action affects many processes including neuronal excitation, synaptic plasticity, and cell death. The use of orexin-SAP (Cat. #IT-20) in some of this work is discussed.

Related Products: Orexin-B-SAP (Cat. #IT-20)

Identification and characterization of a sleep-active cell group in the rostral medullary brainstem.

Anaclet C, Lin JS, Vetrivelan R, Krenzer M, Vong L, Fuller PM, Lu J (2012) Identification and characterization of a sleep-active cell group in the rostral medullary brainstem. J Neurosci 32(50):17970-17976. doi: 10.1523/JNEUROSCI.0620-12.2012

Summary: The authors attempt to locate and identify specific neuronal populations that promote sleep. One method utilized was 130-330 pg injections of orexin-SAP (Cat. #IT-20) into the parafacial zone. These results establish the parafacial zone as a delimited node of sleep-active neurons.

Related Products: Orexin-B-SAP (Cat. #IT-20)

Metabolic effects of chronic sleep restriction in rats.

Vetrivelan R, Fuller PM, Yokota S, Lu J, Saper CB (2012) Metabolic effects of chronic sleep restriction in rats. Sleep 35(11):1511-1520. doi: 10.5665/sleep.2200

Summary: In order to investigate whether there is a correlation between sleep and weight the authors administered 200 nl of a 0.1% solution of orexin-SAP (Cat. #IT-20) to the ventrolateral preoptic area of rats. Although the lesioned animals slept less than the controls, weight gain was slower than controls.

Related Products: Orexin-B-SAP (Cat. #IT-20)

Control of sleep and wakefulness.

Brown RE, Basheer R, McKenna JT, Strecker RE, McCarley RW (2012) Control of sleep and wakefulness. Physiol Rev 92(3):1087-1187 . doi: 10.1152/physrev.00032.2011

Summary: This review summarizes mechanisms in the brain that control sleep and wakefulness. Areas discussed include wakefulness promoting systems, non-REM sleep and REM sleep definitions, the function of each kind of sleep, and dysfunction that occurs as a result of sleep disruption. Several targeted conjugates are mentioned, such as 192-IgG-SAP (Cat. #IT-01), anti-DBH-SAP (Cat. #IT-03), and orexin-SAP (Cat. #IT-20). The review summarizes the use of these products to better understand sleep networks.

Related Products: 192-IgG-SAP (Cat. #IT-01), Anti-DBH-SAP (Cat. #IT-03), Orexin-B-SAP (Cat. #IT-20)

Septohippocampal GABAergic neurons mediate the altered behaviors induced by n-methyl-D-aspartate receptor antagonists.

Ma J, Tai SK, Leung LS (2012) Septohippocampal GABAergic neurons mediate the altered behaviors induced by n-methyl-D-aspartate receptor antagonists. Hippocampus 22(12):2208-2218. doi: 10.1002/hipo.22039

Summary: It is thought that the integrity of the medial septum is essential for the maintenance of hippocampal theta rhythm – and that this maintenance depends on three types of septohippocampal neurons; cholinergic, GABAergic, and glutaminergic. In this work the authors administered bilateral injections totaling 140 ng of orexin-SAP (Cat. #IT-20) into the medial septum of rats. The animals were then treated with NMDA receptor antagonists to examine the role of GABAergic neurons from the medial septum in psychotic behavior. The data suggest that septohippocampal GABAergic neurons are important for expression of psychotic symptoms caused by NMDA receptor antagonists.

Related Products: Orexin-B-SAP (Cat. #IT-20)

Effect of orexin-B-saporin-induced lesions of the lateral hypothalamus on performance on a progressive ratio schedule.

Olarte-Sánchez CM, Valencia Torres L, Body S, Cassaday HJ, Bradshaw CM, Szabadi E (2012) Effect of orexin-B-saporin-induced lesions of the lateral hypothalamus on performance on a progressive ratio schedule. J Psychopharmacol 26(6):871-886. doi: 10.1177/0269881111409607

Summary: It has been suggested that orexigenic neurons in the hypothalamus consist of two anatomically distinct groups. The lateral hypothalamic area group (LHA), which modulates reinforcement mechanisms; and the dorsomedial hypothalamus and perifornical area group involved in regulation of stress and arousal. Rats received bilateral 15 ng injections of orexin-SAP (Cat. #IT-20) into the LHA. Results from a progressive ratio model indicate that the lesioned neurons control the motor component of food-reinforced responding.

Related Products: Orexin-B-SAP (Cat. #IT-20)

Involvement of tuberomamillary histaminergic neurons in isoflurane anesthesia.

Luo T, Leung LS (2011) Involvement of tuberomamillary histaminergic neurons in isoflurane anesthesia. Anesthesiology 115(1):36-43. doi: 10.1097/ALN.0b013e3182207655

Summary: Although previous studies indicate that histaminergic neurotransmission may mediate reaction to general anesthesia, it is not clear whether the histominergic tuberomammilary nucleus (TMN) is involved. Rats received 250-ng infusions of orexin-SAP (Cat. #IT-20) into the TMN after which the righting reflex was assessed for several anesthetics. Loss of histaminergic neurons in the TMN only altered the effect of isoflurane – suggesting that the neural circuits involved in isoflurane anesthesia are different than circuits affected by propofol, pentobarbital, and ketamine.

Related Products: Orexin-B-SAP (Cat. #IT-20)

Histaminergic regulation of seasonal metabolic rhythms in Siberian hamsters.

I’anson H, Jethwa PH, Warner A, Ebling FJ (2011) Histaminergic regulation of seasonal metabolic rhythms in Siberian hamsters. Physiol Behav 103(3-4):268-278. doi: 10.1016/j.physbeh.2011.02.035

Summary: The role of central histaminergic mechanisms on seasonal catabolic state was investigated in hamsters. Siberian hamsters received bilateral 3.8-ng injections of orexin-SAP (Cat. #IT-20) into the tuberomammillary posterior hypothalamic region. Saporin (Cat. #PR-01) was used as a control. During long days, lesioned animals displayed higher locomotor activity, greater oxygen intake, and no net weight gain. During shorter days (hibernation) with less activity, lesioned animals did not lose weight. The data indicate that histaminergic neurons are involved in body weight regulation.

Related Products: Orexin-B-SAP (Cat. #IT-20), Saporin (Cat. #PR-01)

Reassessment of the structural basis of the ascending arousal system.

Fuller P, Sherman D, Pedersen NP, Saper CB, Lu J (2011) Reassessment of the structural basis of the ascending arousal system. J Comp Neurol 519(5):933-956. doi: 10.1002/cne.22559

Summary: Traditional thought has been that electroencephalogram activity is mainly generated by the thalamo-cortical system. In this work the authors investigated the effects of basal forebrain lesions on various measurements of wakefulness. Rats received 4 50 ng injections of 192-IgG-SAP (Cat. #IT-01) into the basal forebrain. The effects of these lesions showed that the parabrachial nucleus/precoeruleus region projection relayed by the basal forebrain to the cerebral cortex plays a critical role in behavioral and electrocortical arousal.

Usage: Lesions of the basal forebrain were done by injecting a 0.1% solution of either 192-IgG-SAP or Orexin-SAP at four different sites.

Related Products: 192-IgG-SAP (Cat. #IT-01), Orexin-B-SAP (Cat. #IT-20)

Orexin-B-saporin lesions in the lateral hypothalamus enhance photic masking of rapid eye movement sleep in the albino rat.

Ocampo-Garces A, Ibanez F, Perdomo G, Torrealba F (2011) Orexin-B-saporin lesions in the lateral hypothalamus enhance photic masking of rapid eye movement sleep in the albino rat. J Sleep Res 20:3-11. doi: 10.1111/j.1365-2869.2010.00864.x

Summary: Photic masking occurs when photic input to the retina interferes with REM sleep. Rats that received 200 ng of orexin-SAP (Cat. #IT-20) into the lateral hypothalamus experienced dramatically less REM sleep during normal light cycles. Placing them in a skeleton photoperiod (brief pulses of light, one in the morning and one in the evening), however, caused REM sleep during the rest phase to return to normal. This data suggests that photic masking may explain some effects of narcolepsy and cataplexy.

Related Products: Orexin-B-SAP (Cat. #IT-20)

Lesions of orexin neurons block conditioned place preference for sexual behavior in male rats.

Di Sebastiano AR, Wilson-Perez HE, Lehman MN, Coolen LM (2011) Lesions of orexin neurons block conditioned place preference for sexual behavior in male rats. Horm Behav 59(1):1-8. doi: 10.1016/j.yhbeh.2010.09.006

Summary: The neuropeptide orexin is important in the feedback mechanisms of food intake and drugs of abuse. This work investigates the role of orexin in sexual reward in male rats. Two 200 ng bilateral hypothalamic injections of orexin-SAP (Cat. #IT-20) were made into each hemisphere. Blank-SAP (Cat. #IT-21) was used as a control. Although it was shown orexin neurons are activated by sexual reward cures, the data suggest that orexin is not essential for sexual performance and motivation.

Related Products: Orexin-B-SAP (Cat. #IT-20), Blank-SAP (Cat. #IT-21)

Septohippocampal pathways contribute to system consolidation of a spatial memory: Sequential implication of gabaergic and cholinergic neurons.

Lecourtier L, de Vasconcelos AP, Leroux E, Cosquer B, Geiger K, Lithfous S, Cassel JC (2011) Septohippocampal pathways contribute to system consolidation of a spatial memory: Sequential implication of gabaergic and cholinergic neurons. Hippocampus 21(12):1277-1289. doi: 10.1002/hipo.20837

Summary: Few studies have examined the role of GABAergic septohippocampal projections in memory consolidation. The authors administered 192-IgG-SAP (400 ng; Cat. #IT-01) and/or orexin-SAP (70 ng; Cat. #IT-20) to the medial septum/vertical limb of the diagonal band of Broca of rats. Spatial memory tests were then administered over several weeks. The data indicate that both GABAergic and cholinergic septohippocampal systems contribute to memory stabilization, possibly in a sequential manner.

Related Products: 192-IgG-SAP (Cat. #IT-01), Orexin-B-SAP (Cat. #IT-20)

Orexin mediates initiation of sexual behavior in sexually naive male rats, but is not critical for sexual performance.

Di Sebastiano AR, Yong-Yow S, Wagner L, Lehman MN, Coolen LM (2010) Orexin mediates initiation of sexual behavior in sexually naive male rats, but is not critical for sexual performance. Horm Behav 58(3):397-404. doi: 10.1016/j.yhbeh.2010.06.004

Summary: In this work the role of endogenous orexin-A and B in male sexual behavior was investigated. Rats received a total of 400 ng of orexin-SAP (Cat. #IT-20) into the hypothalamus in each hemisphere. Blank-SAP (Cat. #IT-21) was used as a control. The lesions facilitated initiation of sexual behavior in naïve males, and reduced anxiety-like behaviors. The data suggest that orexin may play a role in arousal and anxiety related to sexual behavior in naïve animals, but is not critical for performance or motivation.

Related Products: Orexin-B-SAP (Cat. #IT-20), Blank-SAP (Cat. #IT-21)

Endogenous histamine facilitates long-term potentiation in the hippocampus during walking.

Luo T, Leung LS (2010) Endogenous histamine facilitates long-term potentiation in the hippocampus during walking. J Neurosci 30(23):7845-7852. doi: 10.1523/JNEUROSCI.1127-10.2010

Summary: The neurotransmitter histamine is involved in several physiological functions, such as sleep-wake activites, circadian rhythms, learning, and memory. This work examines the role of histamine in modulating synaptic plasticity. Rats received 62.5 ng injections of orexin-SAP (Cat. #IT-20) into the tuberomammillary nucleus (TMN), followed by assessment of long term potentiation (LTP) during different behavioral states. The data indicate that histaminergic neurons in the TMN facilitate basal-dendritic LTP during walking.

Related Products: Orexin-B-SAP (Cat. #IT-20)

Cell transplantation: a future therapy for narcolepsy?

Arias-Carrion O, Murillo-Rodriguez E (2009) Cell transplantation: a future therapy for narcolepsy?. CNS Neurol Disord Drug Targets 8:309-314. doi: 10.2174/187152709788921681

Summary: This review covers the current understanding of narcolepsy and discusses the potential for transplants as a therapeutic treatment. Animal models are summarized, including the use of orexin-SAP (Cat. #IT-20) in rats. The review goes on to suggest that production of orexigenic neuroblasts from stem cells may be a useful therapy.

Related Products: Orexin-B-SAP (Cat. #IT-20)

Medullary circuitry regulating rapid eye movement sleep and motor atonia.

Vetrivelan R, Fuller PM, Tong Q, Lu J (2009) Medullary circuitry regulating rapid eye movement sleep and motor atonia. J Neurosci 29:9361-9369. doi: 10.1523/JNEUROSCI.0737-09.2009

Summary: Data concerning rapid-eye movement (REM) motor atonia in rats has not agreed with results seen in large amount of data from cats. Here the authors traced the medullary networks in rats involved with this REM function. 120-300 ng injections of orexin-SAP (Cat. #IT-20) were administered to 6 different sites in the medulla. Ablation of orexin receptor-expressing neurons in one site in the ventromedial medulla resulted in intermittent loss of muscle atonia, indicating that glutaminergic neurons in this area are key components of the REM atonia circuit.

Related Products: Orexin-B-SAP (Cat. #IT-20)

Hypocretin-2 saporin lesions of the ventrolateral periaquaductal gray (vlPAG) increase REM sleep in hypocretin knockout mice.

Kaur S, Thankachan S, Begum S, Liu M, Blanco-Centurion C, Shiromani PJ (2009) Hypocretin-2 saporin lesions of the ventrolateral periaquaductal gray (vlPAG) increase REM sleep in hypocretin knockout mice. PLoS One 4:e6346. doi: 10.1371/journal.pone.0006346

Summary: Not all connections between narcolepsy and orexin are understood, since orexin neurons are located in the lateral hypothalamus and some sleep functions are controlled by the brainstem. This experiment used 16.5 ng injections of orexin-SAP (Cat. #IT-20) into each side of the ventrolateral periaqueductal gray (v/PAG to) examine these connections. The results indicate that loss of orexin neurons in the v/PAG results in loss of inhibitory control over REM sleep, but does not cause cataplexy.

Related Products: Orexin-B-SAP (Cat. #IT-20)

Medullary circuitry regulating trigeminal motor nucleus phasic activity during rapid eye movement sleep in the rat

Anaclet C, Pedersen NP, Lu J (2008) Medullary circuitry regulating trigeminal motor nucleus phasic activity during rapid eye movement sleep in the rat. Neuroscience 2008 Abstracts 784.16/RR67. Society for Neuroscience, Washington, DC.

Summary: Rapid Eye Movement (REM) sleep or paradoxical sleep is characterized by activation of the cortical and hippocampal EEG, atonia of postural muscles (neck and limbs), and phasic movements of cranial muscles (eyes, chin, ears and whiskers). We have previously established that glutamatergic neurons of the sublaterodorsal tegmentual nucleus (SLD) play a critical role in generating postural muscle atonia during REM sleep. It has been further proposed that the SLD produces REM motor atonia by stimulating spinal inhibitory neurons, which in turn inhibit spinal motor output neurons. It is not known however whether the SLD is also involved in the regulation of tonic and phasic events of cranial muscles during REM sleep (e.g., rapid eye movement, phasic masseter activation). Previous studies have shown that the supraolivary medulla (SOM, dorsal to the inferior olive) and parvocellular reticular (PCRt) nucleus in the medullary reticular formation project to relevant cranial motor nuclei, including: the trigeminal motor nucleus (Mo5), retroabducens region, facial nucleus (Mo7) and hypoglossal nucleus (Mo12). It is therefore possible that either the SOM or the PCRt (or both) may also be involved in regulating cranial muscle activity in REM sleep. To identify the cell groups responsible for REM phasic control of cranial motor nuclei, we examined masseter muscle EMG following cell-specific lesions (anti-orexin B IgG-saporin) of the SLD, SOM or PCRt. Following two weeks of surgical recovery, we recorded the EEG, EMG (neck and masseter muscles) and EOG continuously for two days. Control rats showed significant phasic activation of the masseter muscles, in particular during the second half of REM sleep episodes. This phasic bursting pattern was similar to eye movements during REM sleep. Neither SLD nor PCRt lesions altered the phasic activity of the masseter muscles during REM sleep, although, and as previously reported, SLD lesions did produce REM without atonia in postural muscles. By contrast, lesions in the SOM eliminated phasic activation of the masseter muscles during REM and produced myoclonic twitching of neck muscles. These results indicate that the SOM is involved in the induction of phasic REM activity of masseter muscles, likely via activation of Mo5, whereas SOM projections to the spinal cord are involved in suppression of myoclonic activity of postural muscles.

Related Products: Orexin-B-SAP (Cat. #IT-20)

The retroabducens region is necessary for rapid eye movement (REM) during REM sleep in the rat

Pedersen NP, Anaclet C, Vetrivelan R, Saper CB, Lu J (2008) The retroabducens region is necessary for rapid eye movement (REM) during REM sleep in the rat. Neuroscience 2008 Abstracts 784.15/RR66. Society for Neuroscience, Washington, DC.

Summary: REM sleep is characterized by REMs, atonia of the non-respiratory musculature, and active dreaming during which the electroencephalogram (EEG) is desynchronized in humans and shows increased theta activity in rodents. Surprisingly, the source of the actual REMs during REM sleep is not known, although Pompeiano and Morrison (1965) described the reduction or absence of phasic REM phenomena after electrolytic lesion of the medial and spinal vestibular nuclei in the cat. Using the neurotoxins ibotenic acid and saporin-conjugated anti-orexin B IgG, we systematically placed cell-specific lesions in brainstem candidate structures for the generation of REMs in rats equipped for chronic recording of EEG, electrooculogram, and electromyogram. Lesion of a ‘retroabducens’ area, located immediately caudal and extending ventrally from the abducens nucleus, although leaving the abducens nucleus intact, abolished REMs (as well as waking saccades), without affecting other aspects of REM sleep. Animals with retroabducens lesions showed maintenance of slow oscillations in eye position, characteristic of non-REM or slow wave sleep, throughout REM sleep. Lesions of the medial vestibular nucleus, nucleus prepositus hypoglossi and immediately rostral to abducens did not affect REMs. We hypothesize that the retroabducens area may be required for the generation of saccadic eye movements, similar to the paramedian pontine reticular formation as described in cats and monkeys. The retroabducens region appears to be critical for generating the REMs that characterize REM sleep, but most likely downstream from the REM sleep generator.

Related Products: Orexin-B-SAP (Cat. #IT-20)

Changes in energy metabolism after ventrolateral preoptic lesions in rats

Ramalingam V, Fuller PM, Lu J, Saper CB (2008) Changes in energy metabolism after ventrolateral preoptic lesions in rats. Neuroscience 2008 Abstracts 586.14/SS47. Society for Neuroscience, Washington, DC.

Summary: The ventrolateral preoptic area (VLPO) is critically involved in the regulation of sleep. For example, lesions of the VLPO have been reported to cause profound insomnia and sleep fragmentation in rats. We evaluated possible changes in energy metabolism and motor behaviors secondary to chronic sleep restriction in VLPO lesioned rats. Under anesthesia (chloralhydrate, 350 mg/kg, i.p.), adult male Sprague Dawley rats (n = 17) received stereotaxic injections of orexin-saporin into the VLPO and were also implanted with EEG/EMG electrodes to assess sleep-wakefulness. Food, water, and body mass measurements were collected for 60 post-lesion days. Sleep-wakefulness was recorded on post-lesion Days 20 and 50. On post-lesion Day 60, the animals were deeply anesthetized and transcardially perfused with 10% formaldehyde. The brains were removed and processed for histological verification of the lesion site. VLPO lesions produced a decrease (34%) in non rapid eye movement sleep (NREM) and a decrease in NREM sleep bout duration (115 ± 5 sec in the VLPO lesioned rats Vs 133 ± 2 in control rats, P < 0.01). The VLPO lesioned animals also exhibited increased food intake when compared to the age-matched controls (0.45 ± 0.004 grams per gram of lean body mass Vs 0.39 ± 0.01 grams per gram of lean body mass, P = 0.05). Food intake (r = 0.90, P<0.001), but not water intake was positively correlated with the amount of sleep loss. Although the weight gain in the VLPO lesioned rats was not statistically different from the controls, it was negatively correlated with the amount of sleep loss in those animals (r = 0.51, P = 0.05). Although the VLPO lesioned animals balanced on the rotatrod for 25% less time than the controls, this did not reach statistical significance, perhaps because the variance was so high in both groups (87 ± 23 seconds Vs 116 ± 25 sec in control rats, P>0.05). The close correlation of sleep loss with changes in food intake and body weight after the VLPO lesions suggests that the increased feeding but lower body weight may be due to the sleep loss, rather than a consequence of damaging neurons adjacent to the VLPO, which would not correlate with sleep loss.

Related Products: Orexin-B-SAP (Cat. #IT-20)

The substantia nigra and the control of sleep

Lai YY, Hsieh KC, Nguyen D, Siegel JM (2008) The substantia nigra and the control of sleep. Neuroscience 2008 Abstracts 586.9/SS42. Society for Neuroscience, Washington, DC.

Summary: It has been established that the substantia nigra (SN) is involved in the control of motor activity. However, its role in the regulation of sleep remains unclear. We have previously found that NMDA lesions in the SN suppress sleep in the cat. A recent study demonstrated that lesions of the SN by hypocretin2-saporin result in severe insomnia in the rat. Thus, we hypothesized that activation of the SN by application of either excitatory transmitter analogs/agonists or GABA receptor blockers would induce sleep. Hypocretin had been reported to exert an excitatory effect on SN neuronal activity. The SN receives dense projections from hypocretin neurons. In the current study, we investigated whether microinfusion of hypocretin into the SN would modulate sleep and wakefulness in freely moving rats. Adult male Sprague-Dawley rats were implanted with EEG and EMG electrodes, and a guide cannula targeting the SN. Experiments were conducted one week after the rat had been implanted. The rats were housed individually in sound-attenuated chambers in LD 12:12. Hypocretin-1 was delivered via microdialysis probes (CMA/11) at a rate of 2 μL/min. Each one-hour of hypocretin infusion (ZT4 to ZT5 in the light period) was preceded by a 2-hour baseline period of artificial cerebrospinal fluid (aCSF) infusion and was followed by a 2-hour aCSF infusion. The lower concentration of hypocretin-1 (36 μM, n=2) reduced wakefulness by 19% ± 9.5% and increased slow wave sleep (SWS) by 12.8% ± 2.3% of the baseline level. The higher concentration of hypocretin-1 (72 μM, n=3) reduced wakefulness by 30.5% ± 16.4% of the baseline level and produced an increase in both SWS and REM sleep, by 10.2% ± 2.2% and 63.7% ± 26.6% respectively. The increased sleep induced by both concentrations of hypocretin were also observed in the first post-infusion hour. In conclusion, we found that hypocretin-1 has a sleep-promoting effect in the SN. Our previous study showed that hypocretin (orexin) neurodegeneration occurred in Parkinson’s disease patients. This finding suggests that sleep difficulties in Parkinson's disease patients may result from a combination of lesions in the SN and the secondary effects of the loss of hypocretin neurons.

Related Products: Orexin-B-SAP (Cat. #IT-20)

Unilateral lesions of lateral hypothalamic orexin neurons impair surprise-induced enhancements of learning

Holland PC, Angeli N, Lasseter H, Wheeler DS (2008) Unilateral lesions of lateral hypothalamic orexin neurons impair surprise-induced enhancements of learning. Neuroscience 2008 Abstracts 387.16/SS63. Society for Neuroscience, Washington, DC.

Summary: Recent evidence indicates that hypothalamic orexin (hypocretin) neurons are importantly involved in arousal, aspects of learned motivational function, and the cholinergic mediation of sustained attention and the enhanced detection of weak but significant cues. Here we examined the role of these neurons in the modulation of attention in the associative learning of rats. The surprising omission of an expected event can enhance attention to cues present at the time of surprise, and hence facilitate subsequent learning about those cues. In previous research, we showed that circuitry including the amygdala central nucleus (CeA), the substantia nigra pars compacta, cholinergic neurons in the substantia innominata/nucleus basalis, and portions of the medial prefrontal and posterior parietal cortex, form a network essential for this surprise-enhanced learning. In the present study, rats received orexin-saporin lesions of the lateral hypothalamus (LH) in one hemisphere and ibotenic acid lesions of CeA in the other. Because most projections between LH and CeA are ipsilateral, this combination of lesions functionally disconnects CeA from LH orexin neurons. Rats in three control groups received unilateral lesions of LH or CeA (with sham lesions of the other region) or sham lesions of both regions. The rats were then trained in a task in which attention was manipulated by shifting a predictive relation between two cues. First, all rats received serial light-tone pairings, half of which were followed by food. Next, for half of the rats in each lesion condition the tone was omitted on nonreinforced trials, whereas the remaining rats continued to receive the same light-tone trials as before. Finally, attention to the light was assessed by measuring the rate of learning a new light-food relation. If the rats were surprised by the omission of tone during the previous phase, then attention to the light would be enhanced, resulting in faster acquisition of light-food conditioning. Consistent with previous findings, sham-lesioned rats and rats with unilateral CeA lesions showed this surprise-induced enhancement. By contrast, rats with unilateral LH lesions showed no such enhancement of learning, but otherwise performed comparably to controls. Notably, damage to CeA contralateral to the LH damage produced no additional impairment. Thus, LH orexin neurons play an important role in the surprise-induced enhancement of attention and learning, but not solely by their interactions with CeA.

Related Products: Orexin-B-SAP (Cat. #IT-20)

The role of orexin in sexual behavior and sexual reward of the male rat

Di Sebastiano AR, Yong-yow S, Coolen LM (2008) The role of orexin in sexual behavior and sexual reward of the male rat. Neuroscience 2008 Abstracts 97.4/UU18. Society for Neuroscience, Washington, DC.

Summary: The hypothalamic neuropeptide orexin has been demonstrated to play a role in reward related to drugs of abuse and is potentially involved in regulation of natural rewarding behaviors. Male sexual behavior has been shown to activate orexin neurons and this behavior is altered by administration of orexin receptor agonists or antagonists. However, the exact role of orexin in male sexual performance, sexual motivation and reward is currently unclear. Therefore, the goal of the current study was to test the hypothesis that orexin plays a critical role in sexual behavior, motivation and reward. First, using Fos as a marker for neural activation, we investigated activation of orexin neurons following different parameters of sexual behavior in sexually naïve and experienced male rats. It was demonstrated that orexin neurons in the lateral hypothalamic area (LHA) and in the dorsal medial hypothalamus/perifornical (PFA-DMH) region become activated with presentation of the female and there is no further increase in activation with other components of mating (15-30% in LHA; 65-80% in PFA-DMH). Next, we tested the functional role of orexin utilizing orexin-cell body specific lesions. Adult male rats underwent lesion or sham surgery using the targeted toxin orexin-saporin or blank-saporin respectively. Following two weeks recovery, sexual behavior was recorded over the course of four mating trials. During the first mating trial, males with complete lesions showed significantly shorter latencies to mount and intromit. This suggests that lesions facilitated sexual performance in naïve animals. This facilitation was attenuated by sexual experience as lesions did not affect any parameter of sexual behavior in experienced animals. Next, runway tests were conducted to determine motivation to run towards a potential partner over two conditioning trials. Lesions did not alter sexual motivation, as lesion and sham males all demonstrated increased speed to run towards an estrous female during the second trial. Finally, a conditioned place preference (CPP) paradigm was conducted as a measure of sexual reward. All groups formed a conditioned preference for the mating-paired chamber, indicating that lesions did not significantly disrupt sexual reward. Overall, these findings suggest that orexin does not play a critical role in male sexual performance, motivation, and reward, however may be involved in general arousal related to sexual behavior.

Related Products: Orexin-B-SAP (Cat. #IT-20), Blank-SAP (Cat. #IT-21)

Effects of hypocretin (orexin) neuronal loss on sleep and extracellular adenosine levels in the rat basal forebrain.

Murillo-Rodriguez E, Liu M, Blanco-Centurion C, Shiromani PJ (2008) Effects of hypocretin (orexin) neuronal loss on sleep and extracellular adenosine levels in the rat basal forebrain. Eur J Neurosci 28(6):1191-1198. doi: 10.1111/j.1460-9568.2008.06424.x

Summary: Adenosine levels in the basal forebrain are thought to regulate the waxing and waning of sleep drive. Rats received bilateral 100-ng injections of orexin-SAP (Cat. #IT-20) into the lateral hypothalamus – resulting in a 94% loss of orexin-containing neurons. Lesioned animals displayed several changes in sleep characteristics, but no increase of adenosine levels after sleep deprivation. The results indicate that sleep changes due to orexin-SAP lesioning occur independently of adenosine levels.

Related Products: Orexin-B-SAP (Cat. #IT-20)

Effects of saporin-induced lesions of three arousal populations on daily levels of sleep and wake.

Blanco-Centurion C, Gerashchenko D, Shiromani PJ (2007) Effects of saporin-induced lesions of three arousal populations on daily levels of sleep and wake. J Neurosci 27:14041-14048. doi: 10.1523/JNEUROSCI.3217-07.2007

Summary: Orexin neurons in the basal forebrain, tuberomammillary nucleus (TMN), and locus ceruleus (LC) are thought to regulate arousal. Rats were injected with two or three of the following targeted conjugates: anti-DBH-SAP (Cat. #IT-03), 0.25 µl bilateral injections of 1 µg/µl into the LC; orexin-SAP (Cat. #IT-20), 0.25 µl injection of 0.25 µg/µl into the TMN; 192-IgG-SAP (Cat. #IT-01), 3 µl injection of 2 µg/µl into the lateral ventricle. Small differences were observed in sleep architecture, but the data do not support the traditional hypothesis that these three areas of the brain are essential links in the control of wake levels.

Related Products: Anti-DBH-SAP (Cat. #IT-03), Orexin-B-SAP (Cat. #IT-20), 192-IgG-SAP (Cat. #IT-01)

Food-elicited increases in cortical acetylcholine release require orexin transmission.

Frederick-Duus D, Guyton MF, Fadel J (2007) Food-elicited increases in cortical acetylcholine release require orexin transmission. Neuroscience 149:499-507. doi: 10.1016/j.neuroscience.2007.07.061

Summary: In these experiments the authors examine the hypothesis that orexin fibers from the hypothalamus are necessary for basal forebrain cholinergic system (BFCS) activation in a food restriction model. Rats received 200 ng of orexin-SAP (Cat. #IT-20) into the lateral hypothalamus/perifornical area. Lesioned animals that were also deprived of food displayed increased feeding latency when presented with food. These and other data indicate orexin in the BFCS is involved in attention to stimuli associated with homeostatic challenges.

Related Products: Orexin-B-SAP (Cat. #IT-20)

Transplant of hypocretin neurons into the lateral hypothalamus of a narcolepsy rat model

Millan-Aldaco D, Arias-Carrion O, Palomero-Rivero M, Drucker-Colin R, Murillo-Rodriguez E (2007) Transplant of hypocretin neurons into the lateral hypothalamus of a narcolepsy rat model. Neuroscience 2007 Abstracts 779.2/E4. Society for Neuroscience, San Diego, CA.

Summary: Narcolepsy, a disabling neurological disorder, is characterized by excessive daytime sleepiness, sleeps attacks, sleep fragmentation, and cataplexy. This sleep disorder has been linked to a loss of neurons into the lateral hypothalamus (LH) containing the neuropeptide hypocretin (HCRT). Our group has developed an experimental model in rats that mimics several aberrant behaviours observed in human narcolepsy. The bilateral administration of the neurotoxin hypocretin-2-saporin (HCRT2-SAP) into the LH of rats destroys most of the HCRT neurons (~90%) leading to develop narcolepsy as evaluated using EEG/EMG means. In order to replace the HCRT lost neurons by the local injection of the HCRT2-SAP, a suspension of cells from the hypothalamus obtained from rat pups (3-5 days old) were processed for grafting and stained with GFP. This cell suspension was injected into the LH of lesioned rats and they were sacrificed 21 days post-transplant. The brain was cut and sections containing LH were processed for HCRT immunohistochemistry as well as for the presence of HCRT-immunoflorescence neurons. We were able to differentiate the HCRT transplanted neurons into the LH of lesioned rats. Importantly, they were present at the target area 21 days after implant. These somata were similar in size and appearance to adult rat HCRT-immunoreactive neurons. Our results are very promising since the present study indicates that HCRT neurons obtained from rat pups can be grafted into a host brain and graft survived during 21 days. This experimental approach definitely addresses the possibility to replace HCRT neurons in narcolepsy in order to reverse this disease.

Related Products: Orexin-B-SAP (Cat. #IT-20)

Early activation of the tuberomammillary nucleus is a common factor in appetitive behaviors in rats

Contreras M, Carrasco M, Riveros M, Quispe M, Valdes J, Torrealba F (2007) Early activation of the tuberomammillary nucleus is a common factor in appetitive behaviors in rats. Neuroscience 2007 Abstracts 842.19/WW11. Society for Neuroscience, San Diego, CA.

Summary: Histamine neurons of the tuberomammillary nucleus show an earlier activation during the appetitive phase of feeding, compared to the other arousal system nuclei. To test if in different appetitive behaviors also these histaminergic neurons become active first, we studied changes in Fos-ir in arousal nuclei during sexual, drinking and drug-seeking behavior. Male rats were exposed to sexually receptive or to non-receptive female rats, allowing sensory but not sexual contact. Receptive females elicited increased sniffing time which positively correlated with Fos-ir in the dorsal raphe, laterodorsal tegmental nucleus, orexin hypothalamic neurons and tuberomammillary nucleus. Non receptive females induced less sniffing and no increased Fos-ir. Other male rats were deprived of water for 48 h and presented with an empty water bottle to induce appetitive behavior. The presentation of an empty water bottle to thirsty rats induced increased approaches to the bottle while they tried to drink. While water deprivation per se increased Fos-ir in the dorsal raphe and the locus coeruleus, the presentation of the bottle increased Fos-ir in the tuberomammillary nucleus and induced a further Fos-ir increase in the locus coeruleus. Other male rats were conditioned to amphetamine (1.5 mg/Kg i.p.) using a place preference task. Conditioned rats, but not rats injected with saline instead of amphetamine, showed a significant preference for amphetamine-paired room and increase in the number of Fos-ir in the tuberomammillary nucleus, orexin hypothalamic neurons and locus coeruleus. To evaluate the importance of the histaminergic neurons in the appetitive phase of these motivated behavior, we lesioned tuberomammillary nucleus using saporin conjugated to the hypocretin 2. The histaminergic neurons lesion blunted the appetitive phase in all motivated behaviors studied, without affecting general motor capacities. Taken together our results indicate that the histaminergic neurons become active at the onset of different motivated behaviors and they are key in the arousal that is essential in motivation. Other arousal nuclei may participate depending on the particular behavior.

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Genetic dissection of neural circuitry underlying REM sleep behavior disorder (RBD)

Wood DA, Patterson N, Fuller P, Sherman D, Saper C, Lu J (2007) Genetic dissection of neural circuitry underlying REM sleep behavior disorder (RBD). Neuroscience 2007 Abstracts 736.28/VV11. Society for Neuroscience, San Diego, CA.

Summary: REM sleep behavior disorder (RBD), a parasomnia typically manifested as dream enactment behavior, may represent an early pathophysiologic manifestation of Lewy body diseases (LBD), such as Parkinson disease and dementia with Lewy bodies. Preclinical investigation of possible underlying neural mechanisms of RBD suggests that a set of glutamatergic neurons located in the sublaterodorsal nucleus (SLD), which project to GABA/glycine interneurons in the ventral horn are responsible for atonia during REM sleep (Lu et al. 2006, A putative flip-flop switch for control of REM sleep, Nature 441, 589-94). Based upon these findings, we hypothesize that a loss of glutamate from these neurons in the SLD produces REM sleep without atonia, an animal equivalent of RBD. To assess this question, we selectively eliminated glutamate release from SLD by injecting adeno-associated virus-Cre recombinase (AAV-Cre) into the SLD of mice with lox P sites flanking exon 2 of the vesicular glutamate transporter 2 (VGLUT2) gene. In addition, we examined the role of the ventromedial medulla (VMM) in REM atonia by injecting orexin-saporin in rats and AAV-Cre into flox-VGAT (vesicular GABA/glycine transporter) and flox-VGLUT2 mice. Consistent with our hypothesis, these data show that loss of the VGLUT2 gene in the SLD produces REM sleep without atonia (walking, running and myoclonic jerking) without alteration of total amount of REM sleep. Furthermore, loss of the VGLUT2 but not the VGAT gene in the intermediate VMM results in myoclonic jerking against the background of tonic atonia during REM sleep. Based upon these observations, we propose that suppression of muscle activity during REM sleep is controlled by the activation of excitatory glutamatergic projections from the SLD (with collaterals targeting the intermediate VMM) and from the intermediate VMM, which terminate at inhibitory interneurons in the spinal cord. Collectively, this work provides novel insight into the control of muscle tone during REM sleep, which may have implications for our understanding of neurological conditions that precede the onset of neurodegenerative disease.

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Hypocretin/orexin neuronal loss increases adult neurogenesis

Arias-Carrion O, Hernandez-Martinez H, Drucker-Colin R (2007) Hypocretin/orexin neuronal loss increases adult neurogenesis. Neuroscience 2007 Abstracts 456.14/C7. Society for Neuroscience, San Diego, CA.

Summary: Adult neurogenesis in the subventricular zone (SVZ) is subjected to physiological regulation and can be modified by brain injuries. The sleep disorder narcolepsy may now be considered a neurodegenerative disease, as there is a massive reduction in the number of neurons containing the neuropeptide, hypocretin (HCRT). In the present study, we investigate the relationship between hypocretin neuronal loss and adult neurogenesis. The neurotoxin, hypocretin-2-saporin (HCRT2-SAP), was administered bilaterally to the lateral hypothalamus (LH) to lesion HCRT neurons. Five weeks after HCRT2-SAP administration a loss of HCRT-ir neurons into LH was produced. In normal animals, a high density of HCRT-ir fibers was found in the septum and was poor in the corpus callosum and striatum. These densities decreased in lesioned animals. To label dividing cells, we used 5-bromo-2′-deoxyuridine (BrdU). BrdU was injected twice daily during days 10-14 after lesion, saline or control procedure. Animals were killed at 3 weeks after the last BrdU injection. Experimental depletion of HCRT in rats increases precursor cell proliferation in the SVZ and subependimal layer of 3rd ventricle. However, we don't find BrdU/HCRT double-labeled cells in the subependimal zone or LH. These observations suggest that the HCRT is a negative factor in adult neurogenesis.

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Neurotoxic lesions centered on the perifornical hypothalamus abolish the cardiovascular and behavioral responses of conditioned fear to context but not of restraint.

Furlong T, Carrive P (2007) Neurotoxic lesions centered on the perifornical hypothalamus abolish the cardiovascular and behavioral responses of conditioned fear to context but not of restraint. Brain Res 1128(1):107-119. doi: 10.1016/j.brainres.2006.10.058

Summary: This work examined the role of orexin-containing neurons in the perifornical hypothalamus (PeF) during stress response. Orexin-SAP (Cat. #IT-20) or the control conjugate blank-SAP (Cat. #IT-21) was injected into the PeF of pre-conditioned rats. Tests measuring restraint and conditioned fear to context were then performed on the lesioned animals. While the lesioning was not specific enough to connect results to orexin-containing neurons, the data indicate that the PeF is critical for some forms of stress, but not others.

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Transplant of hypocretin neurons into the lateral hypothalamus of rats with lesions of the hypocretin neurons

Hernandez-Martinez H, Arias-Carrion O, Drucker-Colin R, Murillo-Rodriguez E (2006) Transplant of hypocretin neurons into the lateral hypothalamus of rats with lesions of the hypocretin neurons. Neuroscience 2006 Abstracts 719.2. Society for Neuroscience, Atlanta, GA.

Summary: Narcolepsy, a disabling neurological disorder is characterized by excessive daytime sleepiness, sleeps attacks, sleep fragmentation, and cataplexy. This sleep disorder has been linked to a loss of neurons containing the neuropeptide hypocretin (HCRT). Our group has developed an experimental model to induce narcolepsy in rats. The bilateral administration of the neurotoxin hypocretin-2-saporin (HCRT2-SAP) into the lateral hypothalamus (LH) of rats destroys the HCRT neurons. Therefore, the loss of HCRT neurons leads to developing narcolepsy. In order to replace the HCRT lost neurons by HCRT2-SAP, a suspension of cells from the posterior hypothalamus of 3-5 days old rat pups were stained with GFP and injected into the LH of lesioned rats. Animals were sacrificed 21 days after transplant, and cryostat-cut coronal sections of the LH sections were examined for presence of HCRT-immunofluorescence neurons. Preliminary data shows that HCRT transplanted neurons into the LH of lesioned rats were present at the target area 21 days after implant. These somata were similar in size and appearance to adult rat HCRT-immunoreactive neurons. Our results indicate that HCRT neurons obtained from rat pups can be grafted into a host brain and graft survives during 21 days. Importantly, our study addresses the possibility to replace HCRT neurons in narcolepsy in order to reverse this disease.

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Orexin transmission is required for food-related increases in cortical acetylcholine release

Frederick-Duus D, Fadel J (2006) Orexin transmission is required for food-related increases in cortical acetylcholine release. Neuroscience 2006 Abstracts 369.23. Society for Neuroscience, Atlanta, GA.

Summary: The hypothalamic orexin/hypocretin neuropeptides (OxA and OxB) are crucial modulators of state-dependent behavior including the regulation of arousal in response to homeostatic challenges. Orexins provide a moderately dense innervation of cholinergic portions of the basal forebrain, including the ventral pallidum/substantia innominata and nucleus basalis magnocellularis. OxA administration in this area also produces robust increases in cortical acetylcholine (ACh) release. Here, we used in vivo microdialysis to test the hypothesis that orexin transmission is required for the increase in cortical ACh release resulting from presentation of stimuli related to palatable food. Rats were mildly food-deprived and trained to associate sudden darkness in the testing room with presentation of sweetened cereal. Stimulated cortical ACh release in these animals was blocked by orexin B-saporin (OxB-SAP) lesions of the perifornical hypothalamus at doses that produced 75-80% loss of orexin neurons, but minimal loss of other neuronal phenotypes in this area. In intact animals, pretreatment with the orexin 1 receptor (Ox1R) antagonist SB334867 similarly abolished food cue-elicited increases in cortical ACh release, indicating the specific involvement of OxA in this phenomenon. Neither OxB-SAP nor SB334867 reduced affected basal ACh release. Finally, in old rats (28-30 months), double-label immunohistochemistry revealed a reduction in orexin-immunoreactive fibers near cholinergic somata and dendrites in the basal forebrain regions, consistent with the deficits in stimulated ACh release seen with old animals in this paradigm. Collectively, these data suggest that phasic orexin activation of the basal forebrain cholinergic system may bias attentional resources toward stimuli related to underlying homeostatic challenges, thus coordinating the processing of interoceptive and exteroceptive cues. Age-related deficits in these capacities may have an orexinergic basis.

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A putative flip-flop switch for control of REM sleep.

Lu J, Sherman D, Devor M, Saper CB (2006) A putative flip-flop switch for control of REM sleep. Nature 441(1):589-594. doi: 10.1038/nature04767

Summary: The authors propose a REM sleep regulatory system that involves GABAergic and glutaminergic neurons in the mesopontine tegmentum. Among other work, 2 µl of 0.1% orexin-SAP (Cat. #IT-20) was injected into the medial medullary reticular formation of rats. This work suggests the sharp transitions into and out of REM sleep are controlled by reciprocal interactions between GABAergic REM-off and REM-on neuronal populations.

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Estradiol and orexin-2 saporin actions on multiple forms of behavioral arousal in female mice.

Easton A, Dwyer E, Pfaff DW (2006) Estradiol and orexin-2 saporin actions on multiple forms of behavioral arousal in female mice. Behav Neurosci 120(1):1-9. doi: 10.1037/0735-7044.120.1.1

Summary: Many aspects of female behavioral arousal in response to estrogens are not yet well understood. Here the authors examine the role of orexins as targets for estrogens. Female mice were treated with 10 ng of orexin-SAP (Cat. #IT-20) into each hemisphere of the lateral hypothalamus. The mice were then tested in different modes of behavioral arousal. Mice treated with orexin-SAP displayed decreases in sensory responsiveness and fearfulness concomitant with a reduction in orexin cell number.

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Orexin lesions block food-related increases in cortical acetylcholine release

Fadel J, Frederick-Duus D, Butts R (2005) Orexin lesions block food-related increases in cortical acetylcholine release. Neuroscience 2005 Abstracts 644.8. Society for Neuroscience, Washington, DC.

Summary: Hypothalamic orexin (hypocretin) neurons influence and coordinate arousal, state-dependent behavior, feeding and metabolic processes. Orexin fibers are seen in close proximity to choline acetyltransferase (ChAT)-positive magnocellular somata in portions of the basal forebrain and intrabasalis administration of orexin A increases cortical acetylcholine (ACh) release, suggesting that orexin inputs to the basal forebrain may be important for biasing attentional resources toward stimuli related to underlying homeostatic challenges. Here, we mildly food-deprived rats and trained them to associate an environmental stimulus (darkness) with presentation of palatable food. Microdialysis in these animals showed that the darkness stimulus, with or without accompanying food presentation, produced a robust increase in cortical ACh release. A subset of animals received unilateral administration of the immunotoxin orexin B-saporin (OxB-SAP; 350 ng/0.5 μl) or vehicle into the lateral hypothalamus and perifornical area. OxB-SAP produced a substantial (70-80%) ipsilateral loss of orexin-immunoreactive cells and a corresponding decrease in orexin fiber density in the basal forebrain. OxB-SAP did not alter the number or basal forebrain neurons showing ChAT-immunoreactivity and produced only mild (approximately 15%) loss of melanin-concentrating hormone cells. Basal cortical ACh release was unaffected in lesioned animals, but OxB-SAP lesions abolished increases in cortical ACh release associated with the food-paired stimulus. These data indicate that orexin inputs to the basal forebrain are required for food anticipatory-related increases in cortical ACh release. Orexins appear to be important components of the neural pathways by which interoceptive cues related to homeostasis recruit forebrain attentional systems.

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Hypocretin/orexin neurons and the perifornical hypothalamus play a more important role in contextual fear than in restraint stress

Furlong TM, Carrive P (2005) Hypocretin/orexin neurons and the perifornical hypothalamus play a more important role in contextual fear than in restraint stress. Neuroscience 2005 Abstracts 304.11. Society for Neuroscience, Washington, DC.

Summary: We investigated the role of the neuropeptide hypocretin (Hcrt; also known as orexin) in two different types of stress: conditioned fear to context and restraint stress. For contextual fear, male Wistar rats were tested by re-exposure to a chamber where electric footshocks had previously been administered. For restraint stress, the rats were restrained in tight Plexiglas tubes. In the first study, lesions of the perifornical region of the hypothalamus (PeF; where Hcrt neurons are located) were made with a Hcrt-saporin toxin prior to testing. The cardiovascular response was measured using radio-telemetry. The pressor and tachycardic responses to the context were reduced by 77% and 74% respectively, compared to an intact group (p<0.001, for both comparisons). The lesioned group also displayed significant reductions in freezing (by 67%) and ultrasonic vocalisations (by 74%). In contrast, the cardiovascular response to restraint stress did not differ between the two groups (p>0.5). In the second study, two hours after the tests, the rats were euthanased (200 mg/kg sodium pentobarbitone, i.p) and their brains removed and processed for double immunohistochemical detection of Hcrt and Fos. There was a higher percentage of Hcrt neurons double labeled with Fos after contextual fear (17%) than after restraint stress (6%), which indicates that more Hcrt neurons were active during contextual fear (p=0.024). These studies suggest that the PeF region and Hcrt neurons play a more important role in contextual fear than in restraint stress.

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Adenosine levels do not increase with 6 h waking in rats with lesions of the lateral hypothalamus

Gerashchenko D, Murillo-Rodriguez E, Blanco-Centurion C, Lin L, Nishino S, Mignot E, Shiromani PJ (2005) Adenosine levels do not increase with 6 h waking in rats with lesions of the lateral hypothalamus. Neuroscience 2005 Abstracts 63.9. Society for Neuroscience, Washington, DC.

Summary: The hypocretin neurons in the lateral hypothalamus (LH) have been implicated in wakefulness, but it is not clear which projection is responsible for the arousal. One possibility is that the LH neurons induce wakefulness by driving the basal forebrain (BF) wake-active neurons (Gerashchenko and Shiromani, Cellular & Molec Neurosci, 29: 41, 2004). Here we measure adenosine (AD) levels in the BF as a marker of arousal and test the LH-BF circuit in Sprague-Dawley rats with lesions of the LH induced by hypocretin-2-saporin. 64 days after lesions the rats were kept awake (gentle handling) for six hours (ZT 3-9) and microdialysis samples (5ul) were collected hourly for 9 hours (24h after probe stabilization). AD levels were assessed using HPLC. Hypocretin-saporin ablated 95% of the hypocretin neurons and reduced CSF hypocretin levels (-75% versus control). AD levels increased with 6h waking in saline control rats (n=9), consistent with previous studies in cats (Strecker et al., Behav Brain Res 115: 183, 2000) and rats (Murillo-Rodriguez et al., Neuroscience 123: 361, 2004). However, in rats with LH lesions (n=5) such an increase with waking did not occur. Sleep drive was measured by conducting a rodent version of a multiple sleep latency test (MSLT). In this test, conducted over 10h (from ZT2-ZT12) the rats were kept awake for 20min and then allowed 20min to sleep. The lesioned rats had more sleep during the 20min sleep periods indicating a higher sleep drive. These results suggest that in narcolepsy when the HCRT LH neurons die, there is a loss of stimulation of the wake-active BF neurons and the decline in this pathway may be the cause of the increased sleep attacks. Supported by VA Medical Research and NIH

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Insomnia following hypocretin2-saporin lesions of the substantia nigra.

Gerashchenko D, Blanco-Centurion CA, Miller JD, Shiromani PJ (2006) Insomnia following hypocretin2-saporin lesions of the substantia nigra. Neuroscience 137(1):29-36. doi: 10.1016/j.neuroscience.2005.08.088

Objective: To investigate which regions of major arousal areas might be responsible for the changes in sleep-wake architecture

Summary: It is known that orexin (also known as hypocretin) is involved in waking. The results suggest that motor activity is under inhibitory control of the substantia nigra.

Usage: Bilateral injection of Orexin-SAP (92 and 184 ng/ml, 0.25 ml in the ventral tegmental area and 0.5 ml in the substantia nigra) of rats induced insomnia, as well as hyperactivity and stereotypic movements.

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Orexin-saporin lesions of the medial septum impair spatial memory.

Smith HR, Pang KC (2005) Orexin-saporin lesions of the medial septum impair spatial memory. Neuroscience 132(2):261-271. doi: 10.1016/j.neuroscience.2004.12.037

Summary: The medial septum and diagonal band of Broca (MSDB) have been shown to be important for spatial learning and memory. The authors investigated the role orexin-containing neurons from the hypothalamus play in these processes. Rats were treated with three injections of 40-120 ng of orexin-SAP (Cat. #IT-20) into the MSDB. Performance in spatial working and spatial reference memory tasks indicate that orexin innvervation of the MSDB may modulate spatial memory through both GABAergic and cholinergic septohippocampal neurons.

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Read the featured article in Targeting Trends.

Effects of lesions of the histaminergic tuberomammillary nucleus on spontaneous sleep in rats.

Gerashchenko D, Chou TC, Blanco-Centurion CA, Saper CB, Shiromani PJ (2004) Effects of lesions of the histaminergic tuberomammillary nucleus on spontaneous sleep in rats. Sleep 27(7):1275-1281. doi: 10.1093/sleep/27.7.1275

Summary: Although evidence suggests that histaminergic neurons in the tuberomammillary nucleus (TMN) promote wakefulness, this has not been investigated using specific lesioning agents. In this study, the authors utilize the fact that TMN neurons express the orexin-B receptor by eliminating these neurons with an injection of 50 ng of orexin-SAP (Cat. #IT-20) into the posterior hypothalamus. The data indicate that histaminergic neurons are not required for the homeostatic regulation of sleep.

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Effects of hypocretin2-saporin and antidopamine-beta-hydroxylase-saporin neurotoxic lesions of the dorsolateral pons on sleep and muscle tone.

Blanco-Centurion C, Gerashchenko D, Salin-Pascual RJ, Shiromani PJ (2004) Effects of hypocretin2-saporin and antidopamine-beta-hydroxylase-saporin neurotoxic lesions of the dorsolateral pons on sleep and muscle tone. Eur J Neurosci 19(10):2741-2752. doi: 10.1111/j.0953-816X.2004.03366.x

Summary: Narcolepsy is linked to the loss of orexin (or hypocretin)-containing neurons in the brain. These neurons are located in the perifornical region of the posterior hypothalamus and innervate the locus coeruleus (LC). To investigate the role of the LC in sleep the authors injected 0.3 µl of 192-Saporin (Cat. IT-01) or anti-DBH-SAP (Cat. #IT-03) at 1 µg/µl. They also used 0.3 µl of orexin-SAP (Cat. #IT-20) at either 90 ng/µl or 60 ng/µl in a separate group of animals. The results indicate that orexin innervation to the pons plays a role in arousal from sleep.

Related Products: 192-IgG-SAP (Cat. #IT-01), Anti-DBH-SAP (Cat. #IT-03), Orexin-B-SAP (Cat. #IT-20)

Relationship between CSF hypocretin levels and hypocretin neuronal loss.

Gerashchenko D, Murillo-Rodriguez E, Lin L, Xu M, Hallett L, Nishino S, Mignot E, Shiromani PJ (2003) Relationship between CSF hypocretin levels and hypocretin neuronal loss. Exp Neurol 184(2):1010-1016. doi: 10.1016/S0014-4886(03)00388-1

Summary: Narcolepsy has recently been shown to be a neurodegenerative disease. Data from several different sources indicate that narcoleptics have very low levels of hypocretin (HCRT)-containing neurons. The authors sought to verify a direct linkage between HCRT-containing neurons and HCRT levels in the CSF. Rats were lesioned with 45-90 ng of orexin-SAP (Cat. #IT-20) bilaterally into the lateral hypothalamus. Loss of HCRT neurons correlated with decreased levels of HCRT in the CSF.

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Relationship between CSF hypocretin levels and hypocretin neuronal loss

Gerashchenko D, Murillo-Rodriguez E, Lin L, Xu M, Hallett L, Nishino S, Mignot E, Shiromani PJ (2003) Relationship between CSF hypocretin levels and hypocretin neuronal loss. Neuroscience 2003 Abstracts 616.2. Society for Neuroscience, New Orleans, LA.

Summary: In the sleep disorder narcolepsy there is a massive reduction in the number of neurons containing the neuropeptide, hypocretin (HCRT). Most narcoleptic patients also have low to negligible levels of HCRT in the cerebrospinal fluid (CSF). However, the relationship between HCRT neurons and HCRT levels is not known, making it difficult for investigators to estimate how many HCRT-containing neurons might be present based on measurements of CSF HCRT levels. A relationship between neuronal loss and CSF levels of the ligand is known in other degenerative diseases, such as Parkinson's, but not in narcolepsy. To identify this relationship, hypocretin-2-saporin, the neurotoxin that kills hypocretin neurons, or saline were administered to the lateral hypothalamus and CSF was extracted at zeitgeber times (ZT) 0 (time of lights-on) or ZT 8 at various intervals (2, 4, 6, 12, 21, 36, 60 days) after the neurotoxin administration. Compared to saline animals (n=8), rats with an average loss of 73% of HCRT neurons (n=9) had a 50% decline in CSF HCRT levels on day 60. The decline in HCRT levels was evident by day 6 and there was no recovery or further decrease. The decline in HCRT was correlated with increased REM sleep. Rats with an average loss of 14.4% of HCRT neurons (n=4) showed no significant decline in CSF HCRT levels compared to saline rats. In rats with 73% loss of HCRT neurons, the HCRT levels were not substantially increased by 6h prolonged wakefulness indicating that surviving neurons were not able to increase the output of HCRT to compensate for the HCRT neuronal loss. From these data we conclude that since most narcoleptics have more than 80% reduction of CSF HCRT that in these patients most HCRT neurons are lost.

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Tuberomammillary nucleus lesion decreases the anticipatory events induced by restricted feeding in rats

Recabarren MP, Valdes JL, Seron-Ferre M, Torrealba F (2003) Tuberomammillary nucleus lesion decreases the anticipatory events induced by restricted feeding in rats. Neuroscience 2003 Abstracts 510.19. Society for Neuroscience, New Orleans, LA.

Summary: Our previous studies indicate that the histamine-containing neurons of the tuberomammillary nucleus (TMN) become active in anticipation to feeding time in rats under a restricted feeding schedule. To assess the role of the TMN in this anticipatory activity in rats, we lesioned the TMN bilaterally with stereotaxic injections of 50ng ORX-SAP (Advanced Targeting System, CA). We analyzed the locomotor activity, core temperature and the feeding frequency exhibited by these animals during a restricted feeding protocol, where food was available between 10:00 h and 12:00 h for at least 2 weeks. Rats were implanted in the abdominal cavity with telemetric sensors (Minimitter, OR) to measure locomotor activity and core temperature. During the whole experiment rats were maintained in individual cages and under controlled photoperiod of 12 hours light and 12 hours dark, light were on at 07:00 h. We analyzed the 3 hours preceding food arrival. We checked the extent of TMN destruction by immunostaining the brain sections with antibody against adenosine diaminase (ADA), which colocalize with histaminergic neurons in the TMN. Control rats were subjected to the same procedures except for the injection of the ORX-SAP toxin. Results: Lesion rats showed a significant decrease in the number of ADA-ir neurons in the TMN, as well as a decreased anticipatory activity under restricted feeding in comparison with control rats. Lesion rats although awake before food arrival, were less eager to feed compared to controls, as assessed by food bin approaches. Control rats were slightly more active than lesion rats during restriction. In conclusion, the functional integrity of the TMN is required for the full expression of the anticipatory events that are stimulated by a restricted feeding schedule.

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Targeted toxins in pain.

Wiley RG, Lappi DA (2003) Targeted toxins in pain. Adv Drug Deliv Rev 55(8):1043-1054. doi: 10.1016/s0169-409x(03)00102-9

Summary: The authors discuss the use of 'molecular neurosurgery' in the study of nociception. Applications using targeted toxins, which include immunotoxins, protein-toxin conjugates, or peptide-toxin conjugates, are illustrated. The authors describe the use of these molecules as research tools, as well as their potential for therapeutics. A helpful table is included that lists neuronal surface markers and class of cells targeted for each targeted toxin. Reagents discussed: CTB-SAP (Cat. #IT-14), IB4-SAP (Cat. #IT-10), OX7-SAP (Cat. #IT-02), 192-Saporin (Cat. #IT-01), ME20.4-SAP (Cat. #IT-15), Anti-DBH-SAP (Cat. #IT-03), Anti-DAT-SAP (Cat. #IT-25), SP-SAP (Cat. #IT-07), Dermorphin-SAP (Cat. #IT-12), Orexin-SAP (Cat. #IT-20), CRF-SAP (Cat. #IT-13), and acetylated LDL-SAP (Cat. #IT-08).

Related Products: CTB-SAP (Cat. #IT-14), IB4-SAP (Cat. #IT-10), OX7-SAP (Cat. #IT-02), 192-IgG-SAP (Cat. #IT-01), ME20.4-SAP (Cat. #IT-15), Anti-DBH-SAP (Cat. #IT-03), Anti-DAT-SAP (Cat. #IT-25), SP-SAP (Cat. #IT-07), Dermorphin-SAP / MOR-SAP (Cat. #IT-12), Orexin-B-SAP (Cat. #IT-20), CRF-SAP (Cat. #IT-13), Acetylated LDL-SAP (Cat. #IT-08)

Food- and light-entrained circadian rhythms in rats with hypocretin-2-saporin ablations of the lateral hypothalamus.

Mistlberger RE, Antle MC, Kilduff TS, Jones M (2003) Food- and light-entrained circadian rhythms in rats with hypocretin-2-saporin ablations of the lateral hypothalamus. Brain Res 980(2):161-168. doi: 10.1016/s0006-8993(03)02755-0

Summary: Food-anticipatory behaviors in mammals can follow circadian rhythms entrained by daily feeding schedules. Lateral hypothalamic (LH) neurons express hypocretin (also known as orexin) receptors, therefore rats were treated with four 500-ng injections of orexin-SAP (Cat. #IT-20) to eliminate these neurons. Lesioned animals displayed altered dietary behavior, but maintained anticipatory activity before the daily meal.

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Effects of lateral hypothalamic lesion with the neurotoxin hypocretin-2-saporin on sleep in Long-Evans rats.

Gerashchenko K, Blanco-Centurion C, Greco MA, Shiromani PJ (2003) Effects of lateral hypothalamic lesion with the neurotoxin hypocretin-2-saporin on sleep in Long-Evans rats. Neuroscience 116:223-235. doi: 10.1016/s0306-4522(02)00575-4

Summary: Recent data has linked narcolepsy to the loss of neurons containing the neuropeptide hypocretin, also known as orexin. The authors wished to investigate whether the variance in severity of narcolepsy could be explained by the extent of loss of these neurons. After injection of 90 or 490 ng of orexin-SAP (Cat. #IT-20) into the lateral hypothalamus, the measurement of several parameters demonstrated the severity of narcolepsy may be linked to the degree of loss of neurons expressing the orexin receptor.

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Hypocretin2-saporin (HCRT2-SAP) lesions of the lateral hypothalamus does not affect the entrained or free-running rhythm of core body temperature.

Gerashchenko D, Blanco-Centurion C, Shiromani PJ (2002) Hypocretin2-saporin (HCRT2-SAP) lesions of the lateral hypothalamus does not affect the entrained or free-running rhythm of core body temperature. Neuroscience 2002 Abstracts 776.2. Society for Neuroscience, Orlando, FL.

Summary: Hypocretin (HCRT)neurons are present only in the lateral hypothalamus (LH) from where they project heavily to major arousal centers. HCRT neurons are lost in the sleep disorder narcolepsy, an illness characterized by an increased tendency to fall asleep during the normal active period. As such, it is hypothesized that HCRT neurons are responsible for “waking-up” the brain. To test this hypothesis we monitored the rhythm of core body temperature during entrained & free-run conditions after lesions of the HCRT neurons. 23 male Long-Evans rats implanted with sleep recording electrodes and a temperature transmitter were given one of two concentrations (90 ng/0.5 ìl vs 490 ng/0.5 ìl) of the neurotoxin hypocretin2-saporin (HCRT2-SAP) or unconjugated saporin to the LH. Control rats received saline (n=5). After surgery, sleep and temperature were continuously recorded for 21d in entrained conditions followed by 21d in continuous darkness. Both concentrations of the HCRT2-SAP lesioned HCRT neurons (88% vs 91% HCRT loss). However, HCRT lesions did not disrupt the entrained rhythm of core temperature by either advancing or delaying the phase position of the temperature rhythm. In the saline rats, the free-run period of temperature rhythm (tau) was 24.16 (±0.07) and this was not significantly different in the HCRT2-SAP or SAP rats. These results indicate that in the absence of HCRT, the animal wakes up at the correct time of day but then is not able to stay awake.

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Loss of histaminergic neurons does not produce hypersomnolence.

Chou TC, Gerashchenko D, Saper CB, Shiromani PJ (2001) Loss of histaminergic neurons does not produce hypersomnolence. Neuroscience 2001 Abstracts 522.21. Society for Neuroscience, San Diego, CA.

Summary: Electrolytic lesions of the posterior hypothalamus (PH) produce long-lasting hypersomnolence (1,2). The PH contains histaminergic neurons in the tuberomammillary nucleus (TMN) that project diffusely throughout the brain. Because histamine promotes wakefulness while antihistamines are sedating, the TMN is thought to be critically involved in maintaining wakefulness. To test this hypothesis, we placed cell-specific lesions in the PH and TMN of rats and measured sleep-wake behavior. Lesions were produced using either the conventional excitotoxin ibotenic acid, or the novel toxin orexin (hypocretin) conjugated to the ribosomal toxin saporin (ORX/HCRT-SAP). Ibotenic acid injections were ineffective at lesioning the TMN; most histaminergic neurons were selectively spared while neurons in surrounding regions such as the mammillary bodies and supramammillary area were completely lesioned. In contrast, ORX/HCRT-SAP injections into the TMN lesioned up to 95% of histaminergic neurons, as determined by adenosine-deaminase immunostaining, with a similar loss of neurons in adjacent areas. Surprisingly, neither group of rats showed changes in NREM or REM sleep time or circadian distribution of sleep relative to saline-injected controls for up to 2 weeks after surgery. Thus, the waking state may not be critically dependent on the PH or TMN in rats. Further research is needed to reconcile the sedating effects of antihistamines with the current findings. 1. Ranson 1939, Archiv Neurol and Psychiatry 41(1):1-23. 2. Swett and Hobson 1968, Arch Ital Biol 106(3):283-293.

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Light- and food-entrained circadian rhythms in rats with neurotoxic lesions of hypocretin cells.

Mistlberger RE, Antle MC, Jones M, Kilduff TS (2001) Light- and food-entrained circadian rhythms in rats with neurotoxic lesions of hypocretin cells. Neuroscience 2001 Abstracts 410.8. Society for Neuroscience, San Diego, CA.

Summary: The hypocretins (Hcrt1 & 2) are lateral hypothalamic (LH) neuropeptides implicated in the regulation of feeding and sleep-wake states. Hcrt lesions attenuate the amplitude of sleep-wake circadian rhythms in rats entrained to light-dark (LD; Gerashchenko et al, Soc. Neurosci Abst., 2000). We examined whether Hcrt cells also participate in the expression of circadian rhythms entrained by daily feeding schedules. Rats received LH injections of Hcrt2 conjugated to the ribosome- inactivating protein saporin. Drinking was recorded in LD 12:12 for 1-2 months, in DD for 48 h, and in LD 2:2 for 24 h, to assess photic entrainment and masking. The rats were then restricted to a 3 h daily meal beginning 6 h after lights-on (LD 12:12). After 29 days, the rats were deprived of food for 50 h. Lesions, assessed by immunocytochemistry using preprohypocretin antibody (Chemicon Int., Inc.), ranged from 0-100% complete. Complete lesions were associated with attenuated mean level and amplitude of circadian drinking rhythms in LD 12:12 and DD, but photic masking in LD 2:2 was unaffected. All rats exhibited food-entrained activity that anticipated feeding time by 1-3 h. This was of lower magnitude in the rat with the largest lesion. These results are consistent with a recent report that Hcrt2-saporin lesions attenuate sleep-wake circadian rhythms, but differ from earlier reports that electrolytic lesions of the LH may potentiate the masking effects of light on behavior. The results suggest that Hcrt cells do not play an essential role in the regulation of circadian rhythms by scheduled feeding.

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Hypocretin-2-saporin lesions of the lateral hypothalamus produce narcoleptic-like sleep behavior in the rat.

Gerashchenko D, Kohls MD, Greco M, Waleh NS, Salin-Pascual R, Kilduff TS, Lappi DA, Shiromani PJ (2001) Hypocretin-2-saporin lesions of the lateral hypothalamus produce narcoleptic-like sleep behavior in the rat. J Neurosci 21(18):7273-7283. doi: 10.1523/JNEUROSCI.21-18-07273.2001

Summary: Orexin (also knows as hypocretin) peptides are produced exclusively by neurons in the lateral hypothalamus, however non-specific lesioning in this region has not produced narcoleptic-like sleep. Gerashchenko et al. use orexin-SAP (490 ng/0.5 µl; Cat. #IT-20) to specifically eliminate orexin neurons in rats. The treated rats displayed several sleep disturbances found in narcolepsy, including increased slow-wave sleep, and sleep-onset REM sleep periods. The data suggest that orexin-SAP can be used to create a model for narcolepsy in rats.

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Effects of hypocretin-saporin injections into the medial septum on sleep and hippocampal theta.

Gerashchenko D, Salin-Pascual R, Shiromani PJ (2001) Effects of hypocretin-saporin injections into the medial septum on sleep and hippocampal theta. Brain Res 913:106-115. doi: 10.1016/s0006-8993(01)02792-5

Summary: Hypocretin, also known as orexin, neurons are located only in the lateral hypothalamus. Recently, the loss of these neurons was shown to be associated with narcolepsy. The authors used orexin-SAP (100 ng/0.5 µl; Cat. #IT-20) to eliminate parvalbumin and cholinergic neurons (orexin B receptor-expressing) in the rat medial septum. They used 192-Saporin (1 µg/ 1 µl; Cat. #IT-01) to contrast the effect and eliminate only cholinergic neurons (NGF/p75 receptor-expressing). Hippocampal theta activity was completely eliminated in orexin-SAP treated rats by day 12, suggesting that orexin neurons influence cognitive processes critical for survival.

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Orexin-B conjugated to saporin lesions LH and TMN neurons and produces narcoleptic-like sleep in rats.

Gerashchenko D, Greco MA, Salin-Pascual R, Kilduff TS, Lappi DA, Shiromani PJ (2000) Orexin-B conjugated to saporin lesions LH and TMN neurons and produces narcoleptic-like sleep in rats. Neuroscience 2000 Abstracts 566.27. Society for Neuroscience, New Orleans, LA.

Summary: A dysfunction of the hypocretin/orexin (Hcrt/Ox) system was recently linked with the sleep disorder, narcolepsy. To provide an experimental method that could be used to inactivate Hcrt/Ox receptor bearing neurons, we linked the toxin, saporin, to the orexin receptor binding ligand, orexin-B. Eighteen male Sprague-Dawley rats (400-450 g) were administered orexin-saporin (0.5 ul; 490 ng) to the lateral hypothalamus (LH) (where Hcrt/Ox containing neurons are located) or tuberomammillary nucleus (TMN) (where Hcrt/Ox receptor containing neurons are present) and sleep was recorded for 3 weeks. A significant reduction in the numbers of TMN and Hcrt/Ox neurons in the LH was detected 3 to 5 days after toxin administration and complete loss occurred by 2 weeks. Rats with extensive cell loss exhibited more REM sleep, nonREM sleep, and multiple sleep onset REM periods during the night. In the only two available animal models of human narcolepsy, the dysfunction in the orexin system is inherited and in the entire animal which makes it difficult to localize specific brain regions or circuits underlying narcolepsy. Orexin-saporin provides a method of determining the contribution of a specific Hcrt/Ox innervation in the regulation of behavior.

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Orexins and orexin receptors: a family of hypothalamic neuropeptides and G protein-coupled receptors that regulate feeding behavior.

Sakurai T, Amemiya A, Ishii M, Matsuzaki I, Chemelli RM, Tanaka H, Williams SC, Richardson JA, Kozlowski GP, Wilson S, Arch JR, Buckingham RE, Haynes AC, Carr SA, Annan RS, McNulty DE, Liu WS, Terrett JA, Elshourbagy NA, Bergsma DJ, Yanagisawa M (1998) Orexins and orexin receptors: a family of hypothalamic neuropeptides and G protein-coupled receptors that regulate feeding behavior. Cell 92:573-585. doi: 10.1016/s0092-8674(00)80949-6

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