EFFECTS OF AMPHETAMINE, CHLORPROMAZINE AND PENTOBARBITAL ON BEHAVIORAL THERMOREGULATION

¹ Department of Pharmacology and Experimental Therapeutics and Department of Medicine (Division of Clinical Pharmacology), The Johns Hopkins University School of Medicine, Baltimore, Maryland

The effects of amphetamine, chlorpromazine, and pentobarbital were studied in rats trained to warm themselves in the cold by pressing a lever that turned on a heat lamp. Amphetamine, at a dose level that by itself did not increase the rate at which body temperature fell in the cold, increased the frequency with which the lamp was turned on even though the skin temperature was driven above normal. Chlorpromazine, at a dose level that accelerated heat loss in the cold, decreased the frequency with which the lamp was turned on. Pentobarbital produced only a transient depression directly correlated with dose level. Both amphetamine and chlorpromazine, therefore, impair behavioral regulation, the former by increasing and the latter by decreasing the optimal frequency of bursts of heat. These effects are similar to those observed by investigators who have used food or water to maintain behavior.