Peripheral serotonin is an incomplete signal for eliciting satiety in sham-feeding rats.
Peripheral administration of serotonin [5-hydroxytryptamine (5-HT)] to rats equipped with gastric cannulae reduced their 30-min consumption of sweetened milk after overnight deprivation whether the cannulae were closed (real feeding) or open (sham feeding). The anorectic action of 5-HT (1.6, 4.0, and 10.0 mumol/kg, IP) in sham feeding was dose-related, rapid in onset, and persisted during the 30-min testing session. However, 5-HT failed to elicit resting--the terminal behavioral phase of satiety--in sham-feeding rats. Direct comparison of the effects of 4.0 mumol/kg 5-HT under both feeding conditions established that this dose promoted resting only when rats fed with their cannulae closed. The actions of 5-HT on feeding and resting were behaviorally selective because serotonergic treatment did not retard the beginning of feeding, alter sham drinking of water, or reduce investigation by food-deprived rats of a novel object in an open field. Together, the results suggest that 5-HT exerts separate actions to inhibit feeding and accelerate the process of satiation as marked by resting. However, peripheral 5-HT is inadequate as a signal for modulating satiety in the absence of postingestive stimuli.
Simansky
K J
KJ
Medical College of Pennsylvania, Eastern Pennsylvania Psychiatric Institute, Philadelphia 19129.
Jakubow
J
J
Sisk
F C
FC
Vaidya
A H
AH
Eberle-Wang
K
K
D000818:Animals; D004032:Diet; D004305:Dose-Response Relationship, Drug; D004326:Drinking / Q000187:drug effects; D004435:Eating / Q000187:drug effects; D005106:Exploratory Behavior / Q000187:drug effects; D007274:Injections, Intraperitoneal; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D012528:Satiety Response / Q000187:drug effects*; D012701:Serotonin / Q000008:administration & dosage / Q000494:pharmacology*; D013270:Stomach / Q000502:physiology
D012701:Serotonin