PERSISTING CHANGES IN THE 24-HOUR PROFILE OF LOCOMOTOR-ACTIVITY BY DAILY ACTIVITY RESTRICTION IN RATS

Male Wistar rats were acclimated to cages with running wheels. Then, t he running time of rats were limited to the last 3 (WR3) or 6 (WR6) h of the dark phase. After a 2-week activity restriction, the rats were again allowed access to the wheel freely. In the WR3 or WR6, wheel rev olutions for the last 3 or 6h of the dark phase was significantly grea ter after the activity restriction than before. The results suggest th at, in rats, voluntary running limited to a fixed time daily alters th e distributions of locomotor activity in a day, i.e., running activity increases during the period when the rats had been previously allowed to exercise.