Effects of Temperature, Photoperiod and Food Quantity on Body Mass and Thermogenesis in Apodemus chevrieri

To investigate the influence of different ecological factors in Apodemus chevrieri during the process of seasonal changing, we designed a three-factor experiment of temperature, photoperiod and food quantity in A. chevrieri in the present study. Animals were divided into 8 groups randomly: moderate temperature, longer photoperiod with no food-restricted group; moderate temperature, longer photoperiod with food -restricted group; moderate temperature, shorter photoperiod with no food-restricted group, moderate temperature, shorter photoperiod with food-restricted group; lower temperature, longer photoperiod with no food-restricted group; lower temperature, longer photoperiod with food-restricted group; lower temperature, shorter photoperiod with no food-restricted group, lower temperature, shorter photoperiod with food-restricted group, which were acclimated for 4 weeks. Body mass, resting metabolic rate (RMR) and non shivering thermogenesis (NST), leptin levels and hypothalamic neuropeptide gene expression were measured in each group. The results showed that body mass in A. chevrieri was significantly affected by temperature, food and photoperiod, which was decreased by low temperature, food restriction and short photoperiod. RMR and NST were significantly affected by temperature and food quantity. The content of leptin was significantly affected by temperature, photoperiod and food quantity. Low temperature, short photoperiod and food restriction all decreased the content of leptin. Expression levels of NPY and AgRP were significantly affected by temperature and food quantity. Low temperature and food restriction up-regulated the expression levels of NPY and AgRP. While POMC expression was only affect by food quantity, CART expression was significantly different under the influence of temperature and food quantity. These results suggested that temperature, photoperiod and food quantity had different effects on physiological indexes and energy balance in A. chevrieri, and leptin was involved in the regulation of body mass in A. chevrieri.