The effects of photoperiod and age on food anticipatory activity in Mongolian gerbils (Meriones unguiculatus)

Abstract

In many animal models, the circadian rhythm of locomotor activity is regulated by at least two external pacemakers, environmental photoperiod and food availability. Entrainment with food is characterized by an anticipatory increase in locomotor activity before mealtime. In the present study, the effects of photoperiod and age on the food anticipatory activity (FAA) of Mongolian gerbils were investigated. The experiments were performed under long (14L:10D) and short photoperiods (8L:16D) in young (3 months old) and old (2 years old) adult male gerbils. Food was given only for two hours (11 am–1 pm) during the light phase. Food restriction created FAA in the gerbils. The wheel turn performance of the gerbils was affected by photoperiod, age of the gerbil and food restriction in both light and dark phases. The gerbils experiencing the short photoperiod did perform better than those experiencing the long photoperiod. Young gerbils did perform better than old ones. The light/dark ratio in locomotor activity was affected significantly by photoperiod and food restriction. Food intake of the gerbils was affected by photoperiod, age, and food restriction. In conclusion, photoperiod, age of the gerbil and the food availability were found to be effective in the regulation of FAA in Mongolian gerbils.