Hypothermia in the rat, hamster, ground squirrel and pigeon following chlorpromazine.

Abstract

Body temperature changes induced by two dose levels of chlorpromazine HCl were compared in the rat, hamster, ground squirrel and pigeon. In addition, the effect of cold exposure was determined in the hamster. All three mammalian species showed a rapid decline in temperature by the first 2 hours following the injection of 10 mg/kg body weight of chlorpromazine, after which a gradual return toward normal was evident. However, a further decrease in body temperature occurred at the higher dose level of chlorpromazine (100 mg/kg body weight) and the degree of hypothermia varied with the species. The hamster appeared to be the most resistant to this compound while the ground squirrel was the least resistant. The female of the three mammalian species was less susceptible than the male. The combination of cold exposure and chlorpromazine in the hamster produced a decline in body temperature that was greater than that produced by either stressor alone. Again a sex difference was noted. The pigeon failed to respond to the drug in any degree comparable to that seen in the mammals. This was thought to be due to the lack of effect on respiration, an important thermoregulatory mechanism in the bird.