The effect of D-amphetamine on energy balance in hypothalamic obese rats

Abstract

Young female rats housed in activity-measuring cages were made hyperphagic by placing bilateral lesions in the ventromedial nuclei of the hypothalamus; besides increased food intake, all of them showed reduced locomotor activity. Running could not be stimulated in severely hyperphagic rats by giving D-amphetamine sulfate, although restoration of about half the pre-operative activity occurred in milder hyperphagia. Food consumption was less affected by amphetamine in hyperphagic rats than in normal ones, but the same operated rats became abnormally sensitive to the anorexic action after they became obese. By contrast they were even less active, with or without amphetamine, when obese than when hyperphagic. It is concluded that the ventromedial nucleus is essential to the general stimulant action of the drug, but not to its anorexic effect.