title: d-Fenfluramine and self-stimulation: loss of inhibitory effect in underweight rats.
abstract: The question addressed is whether or not physiological factors associated with body weight, are necessary for serotonergic inhibition of feeding reward. Six rats received the serotonergic drug d-fenfluramine (d-FEN 1.5 and 2.5 mg/kg IP) while they electrically self-stimulated a perifornical lateral hypothalamic (PfLH) site that would induce feeding. As a control, self-stimulation was alternated with stimulation-escape. Both were measured at normal body weight, then at 80% body weight, then normal weight again. Three results were significant. 1) d-FEN markedly suppressed self-stimulation at normal body weight. 2) Self-stimulation rate increased when the animals were put on a diet that reduced body weight to 80% of normal. 3) At this low body weight, d-FEN no longer had any effect on self-stimulation. The results suggest that some correlate of normal food intake or body weight is necessary for serotonergic inhibition of the PfLH feeding-reward system. Possible explanations for fenfluramine's loss of effect at low weight are discussed.
authors.affiliation: Department of Psychology, Princeton University, NJ 08544-1010.
authors.forename: R C
authors.initials: RC
authors.lastname: McClelland
authors.forename: B G
authors.initials: BG
authors.lastname: Hoebel
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D001835:Body Weight / Q000502:physiology*; D004924:Escape Reaction / Q000187:drug effects; D005260:Female; D005277:Fenfluramine / Q000494:pharmacology*; D051381:Rats; D012016:Reference Values; D012653:Self Stimulation / Q000187:drug effects*
chemical_list: D005277:Fenfluramine