sfn2002

Nattie EE, Li A, Richerson G, Lappi D (2002) Specific killing of rat medullary raphe 5-HT neurons by a serotonin transporter antibody-saporin conjugate reduces the ventilatory response to increased CO2 during sleep and wakefulness. Neuroscience 2002 Abstracts 221.3. Society for Neuroscience, Orlando, FL.

Summary: CO2 increases the firing rate of medullary raphe 5-HT neurons in vitro (Richerson et al., Respir. Physiol. 129: 175-190, 2001) and focal CO2 dialysis in the medullary raphe increases ventilation in the sleeping rat (Nattie and Li, J. Appl. Physiol. 90: 1247-1257, 2001). To examine in vivo the relative importance of these 5-HT neurons in chemoreception we used an antibody to the external ring of the serotonin tranport protein (SERT)(SFN abstract #814.9, 2001) conjugated to the cell toxin saporin (SAP). Rat medullary raphe neurons (P0) in culture assayed by TPOH immunoreactivity were killed by 10 and 5 nM SERT-SAP with peak effects at 4 and 7 days, respectively. Non-serotonergic neurons were unaffected. In adult rats after measurement of baseline ventilatory values, we placed EEG/EMG electrodes and injected the SERT-SAP conjugate (1 uM) into the medullary raphe (two adjacent 100 nl injections). There was substantial loss of TPOH but not NK1R immunoreactivity measured at 14 days. There was no effect on ventilation during air breathing awake or asleep. Ventilation during 7% CO2 was significantly decreased in sleep (P < 0.001; repeated measures ANOVA) at days 1, 3, 7, and 14 (-13 to -15%; P < 0.05; Tukey post-hoc test) and in wakefulness (P < 0.01; repeated measures ANOVA) at days 1, 3, 7, and 14 (-10 to -16%; P < 0.05; Tukey post-hoc test). Medullary raphe serotonergic neurons in the rat play an important role in the ventilatory response to systemic hypercapnia during sleep and wakefulness.

Related Products: Anti-SERT-SAP (Cat. #IT-23)

Khasabov SG, Rogers SD, Ghilardi JR, Peters CM, Mantyh PW, Simone DA (2002) Lack of capsaicin (CAP)-evoked sensitization following SP-SAP treatment is not attributed to decreased CAP-evoked exciataion. Neuroscience 2002 Abstracts 351.24. Society for Neuroscience, Orlando, FL.

Summary: The depletion of SPR+ neurons in the spinal cord by substance P-saporin conjugate (SP-SAP) prevents the development of central sensitization, induced by capsaicin (CAP). SP-SAP treatment causes a dramatic decrease in CAP-evoked excitation of remaining nociceptive neurons. The lack of central sensitization after SP-SAP may be due to the decreased excitation of these neurons by CAP. We therefore compared excitation and sensitization following intraplantar injection of different doses of CAP (10 and 100 μg) in rats pretreated intrathecally with vehicle (VEH) or SP-SAP. Injection of 10μg or 100 μg CAP evoked activation and sensitization of nociceptive neurons in VEH-treated rats. Mean responses to von Frey stimuli doubled and heat threshold decreased by about 6˚ C. In SP-SAP rats, 10 μg CAP evoked excitation that was <60% of control whereas 100 μg CAP evoked excitation that was similar to control values. However, sensitization failed to occur following either dose of CAP. In addition, we examined whether effects of SP-SAP was mediated by descending modulation. Transsection of the dorsolateral funiculus increased spontaneous activity of nociceptive neurons in rats pretreated with VEH, but not with SP-SAP. Our data show that the development of central sensitization is dependent on neurons that possess the SPR, and that these neurons appear to be part of a supraspinal loop that modulates descending tonic inhibition.

Related Products: SP-SAP (Cat. #IT-07)

Frick KM, Kim JJ, Baxter MG (2002) Effect of 192-IgG saporin lesions of the entire basal forebrain on emotional and spatial learning. Neuroscience 2002 Abstracts 379.1. Society for Neuroscience, Orlando, FL.

Summary: Scopolamine administration studies suggest that acetylcholine appears to be important for acquisition of contextual fear conditioning (FC), but its involvement in consolidation of fear remains a matter of debate. We examined the role of the basal forebrain cholinergic system in emotional learning and memory by testing male Sprague-Dawley rats with 192 IgG-saporin lesions of basal forebrain cholinergic neurons in contextual and tone FC. Lesions were made either 7 days before (n=10) or one day after (n=10) FC and targeted all basal forebrain nuclei; sham-operated rats (n=5 per condition) served as a comparison. Spatial learning in a one-day water maze task provided a comparison for effects of the lesions on FC. Pretraining lesions had no effect on freezing to tone or context. Posttraining lesions produced a mild impairment in freezing to context, but had no effect on freezing to tone. Both groups were impaired in production of 22 kHz ultrasonic vocalization (USV) associated with fear. Performance on water maze training trials was surprisingly impaired in lesioned rats, although this impairment did not interact with training block and probe trial performance was unimpaired, suggesting that it did not reflect a learning impairment. Radioenzymatic assays of choline acetyltransferase activity in neocortex and hippocampus revealed substantial (>80%) decreases in cholinergic input. These data suggest that conditioned fear-induced USV is more sensitive to the loss of basal forebrain cholinergic neurons than conditioned fear-induced freezing.

Related Products: 192-IgG-SAP (Cat. #IT-01)

Sheriff ST, Xiao C, Chance WT, Kasckow JW, Balasubramaniam A (2002) Selective lesion of neuropeptide Y (NPY)-receptor neurons in hypothalamus inhibit food intake and reduces body weight in rats. Neuroscience 2002 Abstracts 384.1. Society for Neuroscience, Orlando, FL.

Summary: Administration of NPY into hypothalamic areas elicits a most powerful feeding response in rats. The neuronal cell type mediating this orexigenic signal is not clearly understood. To determine the role of NPY-responsive neurons in feeding behavior, we selectively lesioned NPY-receptor neurons by using avidinylated saporin (Av-Sap) mixed with biotinylated NPY. Av-Sap-Biotin NPY complex (ASBN 2.5ug/5ul CSF) or saporin (2ug/4ul CSF) was injected into intracerebroventricle (ICV) of Sprague Dawley rats. Food intake (FI) and body weight was monitored for seven days. On the eighth day NPY (1ug/1ul CSF) was injected into ICV and the FI was monitored for four hours. Injection of ASBN showed a severe reduction in food intake (54%) on the seventh day in comparison to saporin-treated group. ASBN-treated group showed a decrease in the body weight by 24%. The Saporin-treated group showed little body weight reduction (4%). NPY-induced food intake was also reduced in ASBN-treated group. Immunohistochemical analysis revealed a moderate reduction of Y1 receptor (Y1R) neurons in the PVN and arcuate nucleus in this group. Loss of tyrosine hydroxylase neurons in the arcuate nucleus was observed in ASBN-treated group. These results suggest that NPY-receptor neurons may be essential for maintaining the energy homeostasis.

Related Products: Avidinylated-SAP (Cat. #IT-09)

Bradley QR, Borowski TB, de Lacalle S (2002) The effects of 17ß-estradiol on odor discrimination of ovariectomized and intact young and aged rats following unilateral lesions of the nucleus of the horizontal diagonal band of broca (HDB). Neuroscience 2002 Abstracts 385.3. Society for Neuroscience, Orlando, FL.

Summary: Estradiol exerts beneficial effects on cognitive performance. The present study was designed to investigate the effect of estradiol on learning and memory following the destruction of cholinergic neurons of the HDB, a basal forebrain region that exhibits significant neuronal loss during aging and may underlie the cognitive deficits associated with Alzheimers disease. Young (3 months old) and aged (20 months old) ovariectomized and gonadally intact Fisher 344 female rats were given unilateral lesions of the HDB with the cholinergic immunotoxin 192 IgG-saporin (.075mg/ml). Starting one week after surgery rats were tested on an odor discrimination task whereby rats were trained to associate a food reward buried within a scented cup of sand relative to a dissimilar scented cup of sand that contained no reward. Following stable levels of acquisition and retention, subjects were exposed to a reversal procedure where the previously unrewarded cup was now baited. Odor discrimination acquisition, retention and reversal were assessed before and after one month of 17β-estradiol exposure or placebo. Analysis of learning curves revealed that young rats performed better than the aged animals independent of estradiol treatment during the reversal component of the task. However, within each age group 17β-estradiol treatment facilitated performance in ovariectomized rats relative to placebo controls. These findings shed new light on the cognitive enhancing properties of estradiol in age-related cholinergic neurodegenerative disorders.

Related Products: 192-IgG-SAP (Cat. #IT-01)

Hodges MR, Forster HV, Wenninger JM, Brozoski DT, Leekley T, Klum L, Feroah TR, Pan LG, Sengupta J (2002) Effects of lesions in the medullary raphe nucleus on sleep and breathing in adult goats. Neuroscience 2002 Abstracts 321.8. Society for Neuroscience, Orlando, FL.

Summary: The medullary raphe nucleus (MRN) contains populations of both neurokinin-1 and glutamate receptor positive neurons (NK1R+, GluR+). The MRN is also thought to influence breathing during wakefulness and sleep. Therefore, to test the MRN influence on breathing during sleep, adult goats (n=4) were chronically instrumented with microtubules into the MRN and allowed >3 weeks to recover. Sleep was monitored during a period of 6 hours (9pm-3am) prior to and 6-8 days after injection of saporin-substance P (SAP-SP), and the night of and 10-14 days after injection of ibotenic acid (IA). During sleep, EEG, EOG, diaphragm EMG, heart rate and blood pressure were monitored, and arterial blood was sampled. We found no significant effect of neurotoxic lesions on relative percentages of time spent in NREM and REM sleep compared to the post-implant control studies. We also found no evidence of ataxic breathing patterns during awake, NREM or REM states after injection of SAP-SP or IA into the MRN. However, evidence of central apnea was present in 3 of 4 goats. The apneustic events were most frequent during NREM, and less frequent or absent during wakefulness and REM sleep. These apneas were 6-20 seconds in duration and resulted in marked variations in PCO2 and PO2. There was also a tendency for hyperventilation during sleep after IA injections. We conclude that lesions in the MRN by loss of NK1R+ and GluR+ neurons can affect breathing during sleep without affecting sleep itself.

Related Products: SP-SAP (Cat. #IT-07)

Forster HV, Hodges MR, Wenninger JM, Pan LG, Klum L, Leekley T, Feroah TR, Brozoski DT (2002) Breathing of awake goats after neurotoxic lesions in the medullary raphe. Neuroscience 2002 Abstracts 321.9. Society for Neuroscience, Orlando, FL.

Summary: Neurokinin I immunoreactive neurons are abundantly present in the medullary raphe of adult goats. We therefore wished to determine the effect on breathing of destroying such neurons using the neurotoxin saporin (SAP) conjugated to substance P (SP). Injections (1 to 10 µl) of SAP-SP were made at one or two sites in the raphe pallidus and/or raphe obscurus of 4 awake goats. Over the subsequent 5 hours, breathing remained near control levels. Within a few days, there was mild to marked hypoventilation in 2 goats and an attenuated CO2 sensitivity in 3 goats but breathing did not become irregular or ataxic in any goat. The attenuated CO2 sensitivity was associated with evidence of airway constriction. Eight to 14 days later, we injected (1 to 10 µl) at the same sites 50mM ibotenic acid (neurotoxic through glutamate receptors). In the awake state, this injection caused a further marked hypoventilation in one goat who became terminally apneic when anesthetized. After this injection, in the other 3 goats, eupneic PaCO2 was stable and CO2. sensitivity was normal or below normal. We conclude that in awake goats, normal eupneic breathing and CO2 sensitivity are dependent on medullary raphe neurokinin and glutamate receptor activity which apparently includes but is not limited to regulation of airway diameter.

Related Products: SP-SAP (Cat. #IT-07)

Gallegos RA, Lee RS, Crawford E, Wills DN, Carr JR, Zhukov VI, Slaght KE, Huitron-Resendiz S, Criado JR, Henriksen SJ (2002) Selective lesion of ventral tegmental area neurons expressing mu-opioid receptors alters EEG power spectrum across sleep/wake cycle. Neuroscience 2002 Abstracts 276.14. Society for Neuroscience, Orlando, FL.

Summary: The ventral tegmental area (VTA) has long been implicated in motivated behaviors. Our previous study (Lee et al, J Neurosci 2001) also suggests a role for VTA GABAergic neurotransmission in REM sleep. In the current study the potential role of the VTA in modulating electroencephalogram (EEG) activation was explored by selectively deactivating mu-opioid receptor expressing cells in the VTA. Under sodium pentobarbital anesthesia, rats received either (1) a sham operation (2) a single bilateral VTA injection of NMDA (3) a saporin injection or (4) an injection of a dermorphin-saporin (DERM-SAP) conjugate (Advanced Targeting Systems, San Diego). Animals were also fitted with skull electrodes for recording the EEG. The filtered EEG was recorded continuously for 24 hours beginning 21 to 28 days after surgery. Frequency analysis of the EEG in 15-sec epochs revealed differences in the distribution of relative power in the DERM-SAP animals, compared to controls. Low frequency components (0.5-3.0 Hz and 3.0-8.0 Hz) were enhanced in dual lesioned animals during the dark phase but only during sleep. These results indicate that a selective inactivation of cells in the VTA has specific effects on arousal mechanisms in the intact animal.

Related Products: Dermorphin-SAP / MOR-SAP (Cat. #IT-12)

Burgess SE, Gardell LR, Xie Y, Ossipov MH, Vanderah TW, Malan TP, Porreca F, Lai J (2002) Dermorphin-saporin targets descending facilitation in the rostral ventromedial medulla (rvm) to block CCK-induced abnormal pain. Neuroscience 2002 Abstracts 351.11. Society for Neuroscience, Orlando, FL.

Summary: Abnormal pain from L5/L6 spinal nerve ligation (SNL) has been shown to require a time-dependent activation of descending facilitatory pathways arising in the RVM. Additionally, RVM microinjection of L365,260, a cholecystokinin (CCKB) receptor antagonist, reverses SNL-induced tactile and thermal hyperalgesia. These observations suggest the possibility that RVM CCK might “drive” such facilitation from the RVM by activating the endogenous descending facilitation system. Rats were treated with a single RVM injection of dermorphin (DERM) (μ opioid agonist), unconjugated saporin (SAP), or dermorphin-saporin (DERM-SAP) and responses to non-noxious tactile (von Frey filaments) or noxious radiant heat stimuli applied to the hindpaw were measured before and after RVM microinjection of CCK to uninjured rats. RVM DERM-SAP, DERM or SAP did not significantly alter baseline sensory thresholds over 28 days post-injection. At day 28, the rats received bilateral microinjections of CCK (30ng) in the RVM. Rats pretreated with DERM or SAP showed a time-related and revsersible CCK-induced tactile and thermal hypersensitivity. In contrast, RVM CCK failed to produce changes in sensory threshold in animals pretreated with DERM-SAP. The RVM pretreatments did not alter responses in control rats challenged with CCK vehicle. Additionally, lesions of the dorsolateral funiculus also blocked RVM CCK-induced tactile and thermal hypersensitivity. These data support the possibility of CCK-mediated activation of descending facilitation from the RVM as a mechanism of neuropathic pain.

Related Products: Dermorphin-SAP / MOR-SAP (Cat. #IT-12)

Guyenet PG, Stornetta RL, Rosin DL, Wang H, Sevigny CP, Weston MC (2002) Somatostatin immunoreactivity is a diagnostic marker of the pre-Boetzinger complex. Neuroscience 2002 Abstracts 362.4. Society for Neuroscience, Orlando, FL.

Summary: Selective ablation of the neurokinin-1 receptor-ir (NK1R-ir) neurons of the ventral respiratory group (VRG) causes major respiratory deficits. Since this population of NK1R-ir neurons is heterogeneous, additional markers are needed to identify which subgroup is most critical to respiratory rhythmogenesis. In the present study, the pre-Boetzinger complex (pre-BoetC) was defined as a 500 μ-long segment of the ventral respiratory group (VRG) located rostral to the spinally projecting inspiratory premotor neurons. This region of the ventral medulla was the only one that contained somatostatin-immunoreactive (SST-ir) neuronal somata. These cells were small (108 μ²), generally fusiform and they expressed very high levels of preprosomatostatin (PPSST) mRNA. All SST-ir neurons were strongly NK1R-ir and were destroyed by saporin conjugated with an NK1R agonist. Most SST-ir neurons (>90%) contained vesicular glutamate transporter 2 (VGLUT2) mRNA whereas <1% contained GAD-67 mRNA and few (6%) contained preproenkephalin mRNA. The results of retrograde labeling experiments with Fluoro-Gold demonstrated that SST-ir neurons do not project to the spinal cord but that over 75% project to the contralateral pre-BoetC. In conclusion, somatic SST immunoreactivity can be used as a diagnostic marker of the pre-BoetC. The SST-ir cells of the pre-BoetC are small glutamatergic interneurons with contralateral projections and they express high levels of NK1 receptors. The homogeneous features of this group of interneurons and their exclusive location in the pre-BoetC suggest that they could be the NK1R-ir neurons whose destruction disrupts respiratory rhythm. (HL 28785 & 60003).

Related Products: SSP-SAP (Cat. #IT-11)