Cocaine and body temperature in the rat: effects of ambient temperature

The laboratory rat is being developed as a model to determine whether abuse of cocaine constitutes a risk factor in the pathogenesis of stress or exertion-induced heatstroke. Under thermoneutral conditions (Ta 20 degrees C) cocaine (10-40 mg/kg i.p.) caused a dose-dependent fall in core temperature ranging from 0.45 +/- 0.18 to 1.77 +/- 0.26 degrees C. When the ambient temperature (Ta) was increased to 35 degrees C, cocaine (10-40 mg/kg i.p.) led to a dose-dependent hyperthermia (0.3 +/- 0.08 to 1.43 +/- 0.43 degrees C). Repeated injection of cocaine (40 mg/kg at Ta 20 degrees C or 20 mg/kg at Ta 40 degrees C) on days 1, 3, 8, 15, and 23 did not alter the magnitude of the temperature change compared to that following the first injection, i.e., neither tolerance nor potentiation occurred.