Effects of xylamidine on peripheral 5-hydroxytryptamine-induced anorexia.

Rats injected peripherally with 5-hydroxytryptamine (5-HT) showed a dose-dependent decrease in food intake following overnight fasting. The peripheral 5-HT-2 antagonist xylamidine had no effect on food intake when administered alone, but antagonised 5-HT-induced anorexia. However, at the highest dose of 5-HT (5 mg/kg), both doses of xylamidine (1.0 and 2.0 mg/kg) displayed the same degree of antagonism to the anorectic effect, but failed to block it completely. The results are discussed in terms of 5-HT receptor subtypes, and it is suggested that non-5-HT-2 receptors may be partially responsible for the mediation of peripheral 5-HT-induced anorexia.