EFFECTS OF RESTRICTED FEEDING ON THE LIGHT-INDUCED BODY-WEIGHT CHANGEAND LOCOMOTOR-ACTIVITY IN THE DJUNGARIAN HAMSTER

To investigate the role of food intake in seasonal body weight changes in the Djungarian hamster, we divided animals, which had minimum body weights after 18 wk in SD, into ad-lib feeding and restricted feeding groups under a long day (LD) and a short day (SD) photoperiods. In th e ad-lib feeding groups, body weight and food intake increased in para llel after 3 wk under LD and after 6-7 wk in SD because of photorefrac toriness. In the restricted feeding groups, almost all animals moved a round furiously (food-seeking activity) when they came to consume all the food provided at 2-3 wk of the treatment in LD and after several w eeks in SD with the initiation of photorefractoriness, and ended up wi th death. In the restricted feeding groups, body weight increase was n ot observed. The furious food-seeking activity in the restricted group s and the increase of body weight specific food intake (food intake/bo dy weight) in the ad-lib feeding groups might reflect the increased re quirement for food. This increase of requirement for food seems to be one of the critical factors regulating the seasonal body weight change .