EFFECTS OF INDORENATE ON FOOD-INTAKE - A COMPARISON WITH FENFLURAMINEAND AMPHETAMINE

Indorenate (TR3369, 5-methoxytryptamine b-methylcarboxylate HCl) is a 5-HT1-like receptor agonist with hypotensive activity. Here, we descri be that indorenate also decreases food intake (ED(50) 26.1 mg/kg) with out an appreciable effect in water intake (the estimated ED(50) for wa ter was 589.8 mg/kg). The anorectic activity of indorenate was compare d to the effects of amphetamine and other serotonin agonists; the effe ct of indorenate was smaller than those of the other compounds; howeve r, the effect of indorenate was specific to food, whereas all the othe r drugs also produced significant decrements in water intake. The sero tonin antagonists cinanserin, cyproheptadine, methergoline and methyse rgide effectively prevented the decrease in food intake produced by in dorenate and fenfluramine. Haloperidol, a dopaminergic antagonist, was ineffective in preventing the effect of indorenate although it preven ted the anorectic effect of amphetamine. The present results suggest t he participation of serotoninergic, but not dopaminergic mechanisms, i n the decrease in food intake produced by indorenate.