Study On The Regulation Of Hypothalamic Neuropeptide (NPY, AgRP, POMC, CART) In Body Weight And Energy Metabolism

Eothenomys miletus is an endemic species in china, which distributed mainly in Hengduan mountain region and it’s adjacent areas, and it is also an endemic species in Hengduan mountain region.Previous researches showed that role of Ieptin in body mass and energy metabolism regulation were different under diffenent conditions in E. miletus, but the neural mechanism of regulation is still not very clear. In order to further understand the mechanism of Ieptin in the regulation of body mass and energy metabolism in E. miletus, this paper we further researched how about the Ieptin to regulate from the hypothalamic neuropeptide levels, experiments including seasonal acclimation, the single factor experiments of temperature, photoperiod, food and a three factors experiment, finally to investigate the moderating effects of hypothalamic neuropeptide expression on energy homeostasis, determining the adaptation model in E. miletus in Hengduan mountain region, and lays a foundation for further study on the regulation of the hypothalamic neurons in body mass and energy homeostasis in small mammals. The results of the experiment is divided into five parts:1. Effects of hypothalamic neuropeptides genes expression on body mass and energy metabolism under seasonal variation in E. miletus:Body mass and body fat mass showed seasonal variations, which was higher in winter and lower in summer, food intake also showed significant seasonal variability, which was higher in winter and the lowest in winter. Serum Ieptin levels also appeared similar seasonal variation, showed similar trend as body fat mass, Ieptin levels showed a positive correlation with fat content. Expression of hypothalamic neuropeptide NPY and AgRP levels showed significant seasonal differences, while the POMC and CART expression were not significant. Leptin had negative correlation with NPY and AgRP, positive correlation with POMC and CART. The above results showed that E. miletus reduced body mass, body fat mass, increased food intake to survive in winter under seasonal changes. Leptin may play an regulation on body mass and energy metabolism by acting on hypothalamic neuropeptide in E. miletus.2. Effetcs of hypothalamic neuropeptides genes expression on body mass and energy metabolism under cold acclimation in E. miletus:low temperature reduced body mass and body fat mass, and increased food intake. Serum leptin levels showed significant differences between control group and cold exposure group, and leptin levels showed a positive correlation with body fat mass. Hypothalamic neuropeptide NPY expression showed significant different between two groups, while AgRP, POMC and CART expression had not significant differences. Leptin was negatively correlated with NPY, and positively correlated with CART, but not correlated with POMC and AgRP. All of the results suggested that low temperature can reduce the body mass, body fat mass and leptin levels, increased food intake and NPY expression. Leptin may play an regulation on body mass and energy metabolism by acting on hypothalamic neuropeptide of NPY and CART expression in E. miletus.3. Effetcs of hypothalamic neuropeptides genes expression on body mass and energy metabolism under different photoperiods in E. miletus:short photoperiod reduced body mass and body fat mass, and increased food intake. But serum leptin levels showed no significant differences between short photoperiod group and long photoperiod group, and leptin levels showed a positive correlation with body fat mass. Hypothalamic neuropeptide NPY, AgRP, POMC and CART expression had not significant differences between two groups. Leptin was negatively correlated with NPY, but not correlated with CART, POMC and AgRP. All of the results suggested that short photoperiod can reduce the body mass, body fat mass and leptin levels, increased food intake. Leptin may play an regulation on body mass and energy metabolism by acting on hypothalamic neuropeptide of NPY expression in E. miletus.4. Effetcs of hypothalamic neuropeptides genes expression on body mass and energy metabolism under food restriction in E. miletus:food restriction reduced body mass and body fat mass, and increased food intake. Serum leptin levels showed significant differences between control group and food restriction group, and leptin levels showed a positive correlation with body fat mass. Hypothalamic neuropeptide NPY, AgRP, POMC and CART expression showed significant different between two groups. Leptin was negatively correlated with NPY and AgRP, and positively correlated with CART and POMC. All of the results suggested that food restriction can reduce the body mass, body fat mass and leptin levels, increased food intake and hypothalamic neuropeptide expressions. Leptin may play an regulation on body mass and energy metabolism by acting on hypothalamic neuropeptide of NPY/AgRP and CART/CART pathways in E. miletus.5. Effetcs of hypothalamic neuropeptides genes expression on body mass and energy metabolism under different temperature, photoperiods and food resources condition in E. miletus:cold temperature and food restriction reduced body mass, body fat mass and serum leptin levels, and increased NPY and AgRP expression, but decreased POMC and CART expression. Photoperiods had no significant effects on these characters. Leptin was positively correlated with body fat mass, CART and POMC, and negatively correlated with NPY and AgRP. All of the results suggested that temperature and food resources were the key factor to influence the bdoy mass and energy metabolism in E. miletus. Leptin may play an regulation on body mass and energy metabolism by acting on hypothalamic neuropeptide of NPY/AgRP and CART/CART pathways in E. miletus.In summary, E. miletus regulated body mass and energy metabolism by adjusting the hypothalamic neuropeptide expression during seasonal variations, for example, adjusting NPY and CART expression under cold temperature, short photoperiod can increase NPY expression, food restriction can alter NPY/AgRP and POMC/CART expression. For the roles of environmental factors effects, low temperature and food restriction increased NPY and AgRP expression significantly, while decreased POMC and CART expression significantly, but there had no effect of photoperiod on the above index. Changes of hypothalamic neuropeptide expression under seasonal variations and different environment factor acclimation in E. miletus was final to adapt the habitat environment of Hengduan mountainous region:small annual range of temperature, large diurnal temperature range, relatively abundant food resources.