The circadian rhythm of the locomotor activity is regulated by at least 2 external pacemakers, environmental photoperiod and food availability. In the present study, the effects of short-term (2 weeks) food restriction on locomotor activity rhythm in adult male and female Mongolian gerbils were investigated. | Turk J Biol 30 (2006) 23-28 © TÜB‹TAK Food Restriction Affects Locomotor Activity in Mongolian Gerbils (Meriones unguiculatus) Alper KARAKAfi1, Erdinç SER‹N2, Bülent GÜNDÜZ1 1Department 2 of Biology, Faculty of Arts and Sciences, Abant ‹zzet Baysal University, 14280, Bolu - TURKEY Department of Biochemistry, Faculty of Medicine, Abant ‹zzet Baysal University, 14280, Bolu - TURKEY Received: Abstract: The circadian rhythm of the locomotor activity is regulated by at least 2 external pacemakers, environmental photoperiod and food availability. In the present study, the effects of short-term (2 weeks) food restriction on locomotor activity rhythm in adult male 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 long photoperiod (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 ± h) than in females (6 ± h) (P < ). Activity levels and body weights decreased in males (P < ) and females (P < ) 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 gerbil can be entrained by food restriction. Key Words: Rhythm, Food restriction, Locomotor activity, Mongolian gerbil Mo¤olistan Gerbillerinde (Meriones unguiculatus) Besin K›s›tlamas› Lokomotor Aktiviteyi Etkilemektedir Özet: Lokomotor aktivitenin sirkadiyen ritmi en az iki çevresel parametre ile düzenlenebilir, bunlar fotoperiyot ve besin mevcudiyetidir. Bu çal›flmada, k›sa dönem (iki hafta) besin k›s›tlamas›n›n .