Thermoregulation at a high ambient temperature following the oral administration of ethanol in the rat

This study was designed to assess the thermoregulatory mechanisms responsible for the elevation in body temperature following ethanol administration when exposed to a high ambient temperature (Ta). Male rats of the Fischer 344 strain were gavaged with 20% ethanol at doses of 0, 2.0, 4.0, 6.0, or 8.0 g/kg and were then placed in an environmental chamber set at a Ta of 37°C. Metabolic rate normalized to body mass0.75 (MR), evaporative water loss (EWL), and motor activity were recorded for 60 min. Ethanol elicited a significant increase in colonic temperature and decrease in MR, EWL, and motor activity. Ethanol also significantly reduced the quantity of evaporated water per milliliter of oxygen consumed (E/M). Multiple linear regression analysis indicated that the two major factors which were associated with the ethanol-induced elevation in body temperature were an increase in MR and a decrease in E/M. Visual observation of behavior indicated that the normal grooming of saliva onto the fur during heat stress was impaired in ethanol-treated animals. Thus, during exposure to a high Ta, the acute ethanol-induced elevation in body temperature appears to be attributed to a suppression in both autonomic and behavioral mechanisms of heat dissipation.