THE TEMPERATURE RESPONSE OF THE MALE RAT TO TREADMILL EXERCISE, AND THE EFFECT OF ANTERIOR HYPOTHALAMIC LESIONS

Abstract

Male rats exercised on a motor-driven treadmill at a speed of 4.6 meters/minute showed an increase in colonic temperature until it reached a level (39.2–39.5 °C) at which peripheral vasodilatation, as measured by change in skin temperature, occurred in the feet and tail. The colonic temperature then remained at this level above the resting temperature for the duration of exercise. Increasing (6.2 meters/minute) or decreasing (3.2 meters/minute) the speed of exercise resulted in more or less vasodilatation respectively, but did not change appreciably the level at which colonic temperature was regulated during exercise. The colonic temperature at which peripheral vasodilatation first occurred appeared to be a "critical" temperature, being altered by bilateral lesions in the preoptic and anterior hypothalamic areas of the brain.