Effects of sodium salicylate, aminopyrine and chlorpromazine on behavioral temperature regulation.

To characterize drug actions on thermoregulatory processes it is necessary to know whether compounds which alter body temperature also cause changes in thermoregulatory motivation. In the present experiments the effects of sodium salicylate, aminopyrine and chlorpromazine (CPZ) on rectal temperature (Tre) and behavior were measured in rats trained to escape heat and obtain cooling. All three drugs produced hypothermia in a 23 degree C environment but the effects upon behavior suggest that the compounds have different actions. Sodium salicylate (60-300 mg/kg) increased the amount of time spent responding to escape heat and obtain cooling so that Tre was held below control levels. Aminopyrine (12.5-75 mg/kg) did not alter thermoregulatory motivation even though it caused marked hypothemia. The time spent responding decreased after CPZ (2 and 3 mg/kg) so that drug-induced hypothermias were compensated. The results suggest that sodium salicylate influences the central mechanisms of physiological and behavioral temperature control whereas CPZ affects either peripheral thermoeffectors or central effector pathways without disrupting thermoregulatory motivation. Aminopyrine is presumed to act on central temperature controls to lower body temperature and, at the same time, to reduce the significance of the low body temperature to behavior.