Effects of temperature and diet on energy budget and hormone concentrations in south china field mouse,apodemus draco,from hengduan mountain region

Environmental factors play important roles in seasonal adaptation of thermogenesis and hormone concentrations in small mammals. to investigate the roles of temperature and diet in the regulation of energy budget and thermogenesis,adult male apodemus draco were acclimatized to one of 4 groups: 1) cold and low fat diet; 2) cold and high fat diet; 3) warm and low fat diet; 4) warm and high fat diet. after a 7-week acclimation,we determined body mass,energy inatke,resting metabolic rate (rmr),nonshivering thermogenesis (nst),digestive tract morphology,serum leptin level,triiodothyronine (t3),thyroxine (t4) concentrations,mitochondrial protein content (mp),cytochrome c oxidase (cox) activity in liver and brown adipose tissue (bat),and uncoupling protein 1 (ucp1) content in bat. the results showed that cold induced decreases in body mass,body fat mass and serum leptin level,and increases in rmr,nst,cox activity,ucp l content and t3 concentrations. there were no significant effects of diets varying in fat content on body mass,rmr,nst,ucp1 content and serum leptin level. however,high-fat diet significantly reduced energy intake,mass with content and wet mass of the total digestive tract,and elevated digestibility. serum leptin level was positively correlated with body fat mass,however,not with energy intake. our results suggested that a. draco could resist high-fat diet induced obesity,which might be mediated by the increased sensitivity of leptin and enhanced thermogenesis during cold acclimation. it indicated a. draco could prevent excessive obesity by adaptive regulation of energy metabolism and thermogenesis. copyright 2014 zoological society of pakistan.