Effects of chronic cold exposure on wheel running, food intake and fatty acid synthesis in Syrian hamsters.

Mesocricetus auratus with established wheel running in a thermoneutral environment (23 degrees C) showed an immediate suppression of running when placed in a cold room at 4 degrees C. This suppression was seen in three separate studies and lasted at least 1 month. Food intake of these hamsters rose within 48 hr in the cold, and body weight was maintained. In contrast, hamsters which had been sedentary in the 23 degrees C room showed a slower rise in food intake in the cold and sustained a chronic drop in body weight. In vivo fatty acid synthesis rates were greatly elevated in white and brown adipose tissue, but not liver, of exercise versus sedentary hamsters after 1 month in the cold, despite the relative inactivity of both groups throughout the cold exposure. Previous exercise training predisposes hamsters to efficient energy storage in the cold. The energy demand of the cold environment may be responsible for the decreased voluntary running.