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Serotonergic neuronal activity and rhythmic oral-buccal behavior in cats
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ABSTRACTS
Absence of tolerance to the anorectic effects of sulfated cholecystokinin octapeptide (CCK-8). bombesin (BOM) and d-amphetamine sulfate (d-AMPH) when administered chronically to conditioned feeder rats. G. N. ERVIN, M. F. JOHNSON, L. S. BIRKEMO, L. K. CONGER and J. A. MENIUS, JR. Department of Pharmacology and Research Computing, Glaxo Inc. Research Institute, Research Triangle Park, NC 27709, U.S.A.
Male, Long-Evans rats (Charles River Co.) were trained as conditioned feeders for at least 3 weeks, being deprived of food for 7 h (from 0800-1500 hrs), and then being offered a palatable liquid diet (#F1656 or Bio-Serv, Inc.) for 30min (followed with solid chow from 1530 to 0800 hrs). Three groups of trained rats received daily intraperitoneal (i.p.) injections of either CCK-8 [1.75 or 7.0 nanomoles (nMol)/kg body weight], BOM (4.9 nMol/kg), dAMPH [2.7 micromoles (pMol)/kg] or control (0.9% NaCl; 2ml/kg) 15min prior to liquid diet presentation for 31 consecutive days. Compared with control-treated rats (using a multiple analysis of variance, or MANOVA), CCK-8, BOM and d-AMPH-treated rats ate significantly less food over the entire testing period. Two other groups of trained conditioned feeder rats were injected i.p. 15 min before liquid diet presentation with either 7-OnMol/kg CCK-8 or control, 3 days per week (Monday, Wednesday and Friday) for 11 weeks. Then, half of the rats in each group received CCK-8 and the other half received control injections for 31 consecutive days. Again (using MANOVA), CCK-8 was consistently anorectic. Using this conditioned feeding paradigm, our results suggest that tolerance does not develop to these anorectic doses of CCK-8, BOM and d-AMPH.
Serotonergic neuronal activity and rhythmic oral-buccal behavior in cats. C. A. FORNAL, C. W. METZLER, F. MARROSU, K. TADA, L. E. RIBEIRO-DO-VALLE and 6. L. JACOBS. U.S.A.
Depattment of Psychology, Princeton University, Princeton, NJ 08544,
Central serotonergic neurons have been implicated in ingestive behavior. We report here on a subgroup of serotonergic dorsal raphe and nucleus centralis superior neurons that dramatically change their activity in relation to rhythmic oral-buccal motor activities. Serotonergic cells were recorded using movable microwires. Single-unit activity was monitored during spontaneous waking behaviors and during sleep. In addition to highly regular firing serotonergic neurons, we found cells that discharged in a somewhat less regular manner during quiet waking (- 2 spikes/s) and were completely off during REM sleep and in response to systemic administration of serotonin agonist drugs (e.g. 8-OH-DPAT). These cells displayed a two- to five-fold increase in firing rate during feeding, licking, or grooming behavior. Although some of these cells appear to increase their activity in phase with tongue or jaw movement, most of these cells appear to be tonically activated during these rhythmic behaviors. Furthermore, some of these cells exhibited increases in activity several seconds prior to initiating the behavior (e.g. in response to seeing or smelling food) and were also activated by somatosensory stimuli applied to the head and neck area. During other active waking behaviors (e.g. locomotion, orientation) these cells typically decrease their activity. We hypothesize that these serotonergic neurons play a role in modulating central pattern generator mechanisms underlying rhythmic oral-buccal motor activities.
ABSTRACTS
Absence of tolerance to the anorectic effects of sulfated cholecystokinin octapeptide (CCK-8). bombesin (BOM) and d-amphetamine sulfate (d-AMPH) when administered chronically to conditioned feeder rats. G. N. ERVIN, M. F. JOHNSON, L. S. BIRKEMO, L. K. CONGER and J. A. MENIUS, JR. Department of Pharmacology and Research Computing, Glaxo Inc. Research Institute, Research Triangle Park, NC 27709, U.S.A.
Male, Long-Evans rats (Charles River Co.) were trained as conditioned feeders for at least 3 weeks, being deprived of food for 7 h (from 0800-1500 hrs), and then being offered a palatable liquid diet (#F1656 or Bio-Serv, Inc.) for 30min (followed with solid chow from 1530 to 0800 hrs). Three groups of trained rats received daily intraperitoneal (i.p.) injections of either CCK-8 [1.75 or 7.0 nanomoles (nMol)/kg body weight], BOM (4.9 nMol/kg), dAMPH [2.7 micromoles (pMol)/kg] or control (0.9% NaCl; 2ml/kg) 15min prior to liquid diet presentation for 31 consecutive days. Compared with control-treated rats (using a multiple analysis of variance, or MANOVA), CCK-8, BOM and d-AMPH-treated rats ate significantly less food over the entire testing period. Two other groups of trained conditioned feeder rats were injected i.p. 15 min before liquid diet presentation with either 7-OnMol/kg CCK-8 or control, 3 days per week (Monday, Wednesday and Friday) for 11 weeks. Then, half of the rats in each group received CCK-8 and the other half received control injections for 31 consecutive days. Again (using MANOVA), CCK-8 was consistently anorectic. Using this conditioned feeding paradigm, our results suggest that tolerance does not develop to these anorectic doses of CCK-8, BOM and d-AMPH.
Serotonergic neuronal activity and rhythmic oral-buccal behavior in cats. C. A. FORNAL, C. W. METZLER, F. MARROSU, K. TADA, L. E. RIBEIRO-DO-VALLE and 6. L. JACOBS. U.S.A.
Depattment of Psychology, Princeton University, Princeton, NJ 08544,
Central serotonergic neurons have been implicated in ingestive behavior. We report here on a subgroup of serotonergic dorsal raphe and nucleus centralis superior neurons that dramatically change their activity in relation to rhythmic oral-buccal motor activities. Serotonergic cells were recorded using movable microwires. Single-unit activity was monitored during spontaneous waking behaviors and during sleep. In addition to highly regular firing serotonergic neurons, we found cells that discharged in a somewhat less regular manner during quiet waking (- 2 spikes/s) and were completely off during REM sleep and in response to systemic administration of serotonin agonist drugs (e.g. 8-OH-DPAT). These cells displayed a two- to five-fold increase in firing rate during feeding, licking, or grooming behavior. Although some of these cells appear to increase their activity in phase with tongue or jaw movement, most of these cells appear to be tonically activated during these rhythmic behaviors. Furthermore, some of these cells exhibited increases in activity several seconds prior to initiating the behavior (e.g. in response to seeing or smelling food) and were also activated by somatosensory stimuli applied to the head and neck area. During other active waking behaviors (e.g. locomotion, orientation) these cells typically decrease their activity. We hypothesize that these serotonergic neurons play a role in modulating central pattern generator mechanisms underlying rhythmic oral-buccal motor activities.