A dose-response study of anorectic drug effects on food intake, self-stimulation, and stimulation-escape.

A comparison was made of the short-term effects in rats of 3 anorectic drugs (amphetamine, fenfluramine, and phenylpropanolamine) on food intake and responses to obtain brain stimulation and to escape from automatic brain stimulation. At a dose which decreased food intake, amphetamine increased self-stimulation, but not stimulation-escape. Fenfluramine decreased both self-stimulation and stimulation-escape. Phenylpropanolamine, on the other hand, decreased self-stimulation, but not stimulation-escape. Even though all 3 drugs decreased food intake, each of them had different effects on hypothalamic self-stimulation and stimulation-escape. Only the actions of phenylpropanolamine were in agreement with the hypothesis that lateral hypothalamic reward and aversion reflect the animal's tendency to eat, suggesting that other aspects of reinforcement are also involved in lateral hypothalamic stimulation and were affected differently by these drugs.