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Sleep patterns in the genetically obese Zucker rat
204
ABSTRACTS
by the potent, highly selective CCK receptor antagonist MK 329 (L 364,718) (l&lOOpg/kg s.c.). MK 329 by itself did not affect food intake. We propose a 5-HT, control over endogenous CCK activity at CCK sites. Characterization of [1251]-CCK-8 Binding Sites in Rat Vagus Nerve. E. S. CORP, T. H. MORAN and G. P. SMITH. Bourne Laboratory, NYU-Cornell Medical Center and Department of Psychiatry, Johns Hopkins University School of Medicine, NY, U.S.A. Since vagally transported CCK receptors may mediate CCK-8’s satiety effect, we used in vitro autoradiography and computer densitometry to characterize parameters of [‘251]-CCK-8 equilibrium binding to slide-mounted sections of cervical vagus (CV) and subdiaphragmatic vagus (SV) nerve which had been ligated 24 h prior to extraction. Saturable binding sites accumulated proximal (measurable area = @72 to 1.26 mm*) and distal (measurable area = 0.23 to 0.46mm2) to the ligatures in both CV and SV samples. Analysis (non-linear regression) resolved [ 1251]-CCK-8 binding to a single class of CV sites with a K, of 0.78f0.37t-1~ (B,,,= 6.9 fmol/mg tissue), and to a single class of SV sites with a K, of 0.24kO.11 nM (B,,,= 4.8 fmoljmg tissue). Sleep
Patterns
in the
CNRS UA 637, Neurobiologie France.
Genetically
Obese
des RBgulations,
Zucker Rat. JABER DANGUIR. Collt?ge de France, 75231 Paris Cedex 05,
Sleep patterns were continuously recorded in the genetically obese Zucker rat. Under normal feeding conditions, Zucker rats showed large amounts of slow-wave sleep (SWS) and normal amounts of paradoxical sleep (PS). In addition, both SWS and PS were equally distributed throughout the nycthemeron. When acarbose (an a-glucosidase inhibitor that slows absorption of glucose, reduces plasma insulin and increases plasma somatostatin) was added to food pellets, the daily duration of SWS was markedly decreased, whereas PS was significantly increased. These results clearly show that sleep in the Zucker rat differs substantially from that classically observed in normal lean rats. In addition, they suggest that anomalies of insulin and somatostatin production and/or levels may cause the sleep disturbances observed in Zucker rats. Food Intake in Rats is Increased by lntracerebroventricular Infusion of the Somatostatin Analogue SMS 201-995 and is Decreased by Somatostatin Antiserum. JABER DANGUIR. CNRSlJA637, Coll&gede France, Paris, France. The chronic intracerebroventricular infusion of the somatostatin analogue SMS 201-995 resulted in a significant increase in daily food intake which was accompanied by an unexpected body weight loss. The neutralisation of central somatostatin using a specific somatostatin antiserum resulted in a significant decrease in daily food intake. These results suggest that endogenous somatostatin in the brain can drive feeding behaviour and alter body weight. Analysis Sucrose
of the Microstructure of the Licking Behavior of Rats Ingesting and Maltose. JOHN D. DAVIS and GERARD P. SMITH. University of lllinois
Chicago and New York Hospital-Cornell
Medical
Center, White Plains, NY, U.S.A.
The microstructure of licking behavior of rats ingesting liquids consists of bursts of licking at a high rate separated by pauses of varying duration. We analyzed this pattern by measuring the number oflicks in a burst and the length of the intervals between them during the first and second half of an ingestion interval when the animals were exposed to five different concentrations of sucrose and maltose. For both compounds average burst size was the same in the first and second half of the ingestion interval, but the intervals between them were longer in the second half. We conclude that satiety is characterized by increased interburst intervals rather than by a change in burst size.
ABSTRACTS
by the potent, highly selective CCK receptor antagonist MK 329 (L 364,718) (l&lOOpg/kg s.c.). MK 329 by itself did not affect food intake. We propose a 5-HT, control over endogenous CCK activity at CCK sites. Characterization of [1251]-CCK-8 Binding Sites in Rat Vagus Nerve. E. S. CORP, T. H. MORAN and G. P. SMITH. Bourne Laboratory, NYU-Cornell Medical Center and Department of Psychiatry, Johns Hopkins University School of Medicine, NY, U.S.A. Since vagally transported CCK receptors may mediate CCK-8’s satiety effect, we used in vitro autoradiography and computer densitometry to characterize parameters of [‘251]-CCK-8 equilibrium binding to slide-mounted sections of cervical vagus (CV) and subdiaphragmatic vagus (SV) nerve which had been ligated 24 h prior to extraction. Saturable binding sites accumulated proximal (measurable area = @72 to 1.26 mm*) and distal (measurable area = 0.23 to 0.46mm2) to the ligatures in both CV and SV samples. Analysis (non-linear regression) resolved [ 1251]-CCK-8 binding to a single class of CV sites with a K, of 0.78f0.37t-1~ (B,,,= 6.9 fmol/mg tissue), and to a single class of SV sites with a K, of 0.24kO.11 nM (B,,,= 4.8 fmoljmg tissue). Sleep
Patterns
in the
CNRS UA 637, Neurobiologie France.
Genetically
Obese
des RBgulations,
Zucker Rat. JABER DANGUIR. Collt?ge de France, 75231 Paris Cedex 05,
Sleep patterns were continuously recorded in the genetically obese Zucker rat. Under normal feeding conditions, Zucker rats showed large amounts of slow-wave sleep (SWS) and normal amounts of paradoxical sleep (PS). In addition, both SWS and PS were equally distributed throughout the nycthemeron. When acarbose (an a-glucosidase inhibitor that slows absorption of glucose, reduces plasma insulin and increases plasma somatostatin) was added to food pellets, the daily duration of SWS was markedly decreased, whereas PS was significantly increased. These results clearly show that sleep in the Zucker rat differs substantially from that classically observed in normal lean rats. In addition, they suggest that anomalies of insulin and somatostatin production and/or levels may cause the sleep disturbances observed in Zucker rats. Food Intake in Rats is Increased by lntracerebroventricular Infusion of the Somatostatin Analogue SMS 201-995 and is Decreased by Somatostatin Antiserum. JABER DANGUIR. CNRSlJA637, Coll&gede France, Paris, France. The chronic intracerebroventricular infusion of the somatostatin analogue SMS 201-995 resulted in a significant increase in daily food intake which was accompanied by an unexpected body weight loss. The neutralisation of central somatostatin using a specific somatostatin antiserum resulted in a significant decrease in daily food intake. These results suggest that endogenous somatostatin in the brain can drive feeding behaviour and alter body weight. Analysis Sucrose
of the Microstructure of the Licking Behavior of Rats Ingesting and Maltose. JOHN D. DAVIS and GERARD P. SMITH. University of lllinois
Chicago and New York Hospital-Cornell
Medical
Center, White Plains, NY, U.S.A.
The microstructure of licking behavior of rats ingesting liquids consists of bursts of licking at a high rate separated by pauses of varying duration. We analyzed this pattern by measuring the number oflicks in a burst and the length of the intervals between them during the first and second half of an ingestion interval when the animals were exposed to five different concentrations of sucrose and maltose. For both compounds average burst size was the same in the first and second half of the ingestion interval, but the intervals between them were longer in the second half. We conclude that satiety is characterized by increased interburst intervals rather than by a change in burst size.