Peripherally administered alpha-methyl-5-hydroxy-tryptamine and 5-carboxamidotryptamine reduce food intake via different mechanisms in rats.
Peripherally administering the serotonin (5-HT) analogs, alpha-methyl-5-hydroxytryptamine (alpha-Me-5-HT) and 5-carboxamidotryptamine (5-CT), reduced milk consumption by food-deprived rats. 5-CT decreased milk intake 100-fold more potently than alpha-Me-5-HT (ID(50)'s =.06 and 5.6µmol/kg, respectively). 5-CT also elicited drinking but alpha-Me-5-HT did not. The nonselective 5-HT antagonist, methysergide, blocked the anorectic actions of each agonist. By contrast, the 5-HT(2) antagonist, ketanserin, and the peripheral 5-HT(2) antagonist, xylamidine, only prevented anorexia due to alpha-Me-5-HT. These results suggest that stimulating either peripheral 5-HT(2) or peripheral 5-HT(1)-like receptors inhibits feeding in rats. 5-HT(1)-like sites may also mediate 5-HT-induced drinking.
Department of Pharmacology, Medical College of Pennsylvania at Eastern Pennsylvania Psychiatric Institute, 3200 Henry Avenue, Philadelphia, PA 19129, USA.
K.J.
KJ
Simansky
F.C.
FC
Sisk
A.H.
AH
Vaidya
K.
K
Eberle-Wang