Effects of a nitric oxide synthase inhibitor on hypophagia induced by the peripheral 5-HT receptor agonists, α-methyl-5-hydroxytryptamine and 5-carboxamidotryptamine in rats

Abstract

We investigated the effects of the nitric oxide (NO) synthase inhibitor, NG-nitro-L-arginine methyl ester (L-NAME) on hypophagia in rats elicited by α-methyl-5-hydroxytryptamine (α-methyl-5-HT) and 5-carboxamidotryptamine (5-CT) which are suggested to be mediated by the peripheral 5-HT2A and 5-HT7 receptor, respectively. Both α-methyl-5-HT and 5-CT apparently inhibited food intake in food-deprived rats. L-NAME significantly enhanced α-methyl-5-HT-elicited hypophagia, while it inhibited 5-CT-elicited hypophagia. These results suggest that NO is differentially related to α-methyl-5-HT and 5-CT-induced hypophagia and that NO may play a role in hypo- and hyperphagia.