Lesions of the area postrema attenuate but do not prevent the
anorectic action of peripheral serotonin (5-ht) in rats.
Adipudi, V., and K. J. Simansky.
Department of Pharmacology, Medical College of Pennsylvania and
Hahnemann University, Philadelphia, Pennsylvania 19129
APStracts 2:0169R, 1995.
These studies assessed the effect of selectively ablating the area
postrema (AP) on the action of peripheral serotonin (5-HT) to reduce
food intake in rats. Intraperitoneal 5-HT (0, 2.0, 4.0 and 8.0
[mu]mol/kg) reduced the intakes of sweetened mash during a 30-min
test in controls (APC) and in AP-lesioned rats (APX). The anorexia
was dose dependent in controls but the dose-response function was
flat after AP lesions. In another study, 2.0 [mu]mol/kg 5-HT reduced
intakes of both groups by approximately 25% but AP lesions blunted
the effect at 8.0 [mu]mol/kg 5-HT (APX, -30% vs. APC, -85%).
Behavioral analysis revealed that, compared to controls, AP lesions
eliminated the decrease in frequency of feeding and reduced the
incidence of resting and of an aberrant posture observed after 8.0
[mu]mol/kg. Thus, peripheral 5-HT decreases food intake in rats with
AP lesions. Multiple mechanisms appear to be involved in the ability
of peripheral 5-HT to reduce feeding. A high dose of 5-HT promotes
responses associated with satiation but also produces behavioral
toxicity; these effects involve the AP. Lower doses appear to engage
processes that do not rely upon the function of this
circumventricular organ.
Received 9 February 1995; accepted in final form 20 June 1995.
APS Manuscript Number R101-5.
Article publication pending Am. J. Physiol. (Regulatory Integrative
Comp. Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 11 July 1995.