Food Restriction Affects Locomotor Activity in Mongolian Gerbils (Meriones unguiculatus)

The circadian rhythm of the locomotor activity is regulated by at least 2 external pacemakers, environmental photoperiodand food availability. In the present study, the effects of short-term (2 weeks) food restriction on locomotor activity rhythm in adultmale and female Mongolian gerbils were investigated. Animals were fed ad libitum with no restriction during the first week of the experiment and their daily ad libitum food consumptions were determined. Then the food was restricted 40% of ad libitum for the next 2 weeks. At constant temperature, locomotor activity was monitored by running wheel in animals exposed to a longphotoperiod (14L) for 3 weeks. A significant phase advance was recorded in the locomotor activity rhythm in both male and female animals. The shift was bigger in males (12 ± 1.1 h) than in females (6 ± 0.5 h) (P 0.05). Activity levels and body weights decreased in males (P 0.01) and females (P 0.012) compared with the first week values. The gerbils locomotor activity was significantly affected by the food restriction. These results indicate that the rhythm and the level of the locomotor activity in the Mongolian gerbilcan be entrained by food restriction.