Cold increases and warmth diminishes stress-induced rise of colonic temperature in rats.

It is generally believed that the rise of core temperature of rats induced by handling is due to a shift of set-point temperature as in fever. Changes in core temperature due to set-point shifts should not be affected by changes in the ambient temperature. Nevertheless, when the colonic temperature of rats was taken in a cold environment the usual emotional rise was higher and when the colonic temperature was taken in a warm environment the emotional rise was lower. These results contradict the hypothesis that the emotionally induced rise in temperature of rats is a fever.