Cocaine and body temperature in the rat: effect of exercise.

The laboratory rat is being studied as a model to determine if abuse of cocaine constitutes a risk factor in the pathogenesis of stress or exertion induced heatstroke. During running on a treadmill for 60 min under thermoneutral conditions (Ta 22 degrees C) a rise in core temperature of approximately 1 degree C was recorded. Injection of cocaine (10 or 20 mg/kg IP) or its vehicle (0.9% NaCl solution) did not modify the running behavior or the core temperature change. Cocaine (30 mg/kg IP) led to a significant increase in the core temperature (compared to animals treated with saline or the lower doses of cocaine) at 45 and 60 min. The rats recovered rapidly following cessation of exercise. Repeated (3) injections of cocaine (30 mg/kg) at 7-day intervals did not alter the magnitude of the final hyperthermia, i.e., neither tolerance nor potentiation were in evidence.