Effect of fenfluramine on the electrical activity of the hypothalamic feeding centers

Abstract

Electrodes were stereotaxically implanted in the lateral hypothalamic feeding center and medial satiety center as well as in other hypothalamic and cerebral regions in male rhesus monkeys. Electrical activity of these regions was recorded electroencephalographically, before and following iv injections of Fenfluramine given daily for 7-10 days in doses of 1.5 mg/kg and 3 mg/kg body-weight respectively. In addition changes in the eating behavior, daily food intake, body weight and general behavior were observed. In another set of animals arteriovenous glucose differences (to provide indices of glucose utilization in the body) in response to Fenfluramine injections were estimated. Fenfluramine in doses of 1.5 mg/kg gradually resulted in slow wave activity in the feeding center, which became more pronounced after subsequent injections thus demonstrating a cumulative effect. This coincided with anorexic behavior and decrease in food intake. The activity of the satiety center changed to low voltage fast response, specially in starving animals. Arteriovenous glucose estimations suggest that the effects of Fenfluramine may be due to the increased level of glucose utilization in the body. Injections in doses of 3 mg/kg however produced a generalized drowsy response.