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)

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)

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)

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)

Chen L, Brown RE, McKenna JT, McCarley RW (2009) Animal models of narcolepsy. CNS Neurol Disord Drug Targets 8(4):296-308. doi: 10.2174/187152709788921717 PMID: 19689311

Objective: To provide information to enable a consensus concerning the evaluation of narcoleptic behavioral and EEG phenomenology in these models.

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

See Also:

• Gerashchenko K et al. Effects of lateral hypothalamic lesion with the neurotoxin hypocretin-2-saporin on sleep in Long-Evans rats. Neuroscience 116:223-235, 2003.

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)

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)

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)

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.

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

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.

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