The Study Of The Mechanism Of Energy Balance During The Hibernation And Fatten Period Of Daurian Ground Squirrels (Spermophilus Dauricus)

Some small mammals adopt hibernation to cope with the hash environment of winter. Fat-storing hibernators mainly utilize the fat stored in body as the fuel of the whole winter. Some of fat-storing hibernators have food-intakes in winter. The food, as one kind of available energy, and fat may impact the patterns of hibernation. Food intake and energy balance were regulated by leptin, which was produced by WAT, and the leptin-regulated peptides in hypothalamus. In this paper, we use Daurian ground squirrels (Spermophilus dauricus), the typical fat-storing hibernator, as the model animal, investigate the mechanism of neuroendocrine regulation of food intake and energy balance during the different stages of fatten period and hibernation. We also study the impacts of availability of food on the expression of hibernation. Furthermore, we study the differences of thermogenesis in cell levels among the individuals who own the different state of hibernation. Here are the results and conclutions:1. We successfully test the gene expression of long isoform of leptin receptor Ob-Rb and the peptides related with food intake and energy balance (NPY, AgRP, POMC, CART and SOCS-3) in hypothalamus of Daurian ground squirrel by real-time PCR method. During the experiment, we sequenced the gene fragments of some peptides in hypothalamus and proved the basic data for the further research of Daurian ground squirrel's hibernation and energy balance.2. We investigated the central pathway of leptin's regulation on food intake and energy balance with real-time PCR method. The genes expression of leptin receptor, the appetite-stimulated peptides NPY and AgRP, the anorectic peptides POMC and CART, leptin-inducible inhibitor of leptin signaling SOCS-3 were tested in this paper. The results show that:during the fatten period (June and July), high dense of serum leptin inhibited the expression of NPY whereas stimulated the expression of CART. These changes of expression did not inhibit the food intake. The lower expression of POMC might be a factor to keep the high food intake. The relatively high expression of POMC before hibernation (August) might be one factor to reduce the food intake. Conclusions:there was leptin resistance during fatten period of mammalian hibernator; the expression of POMC in hypothalamus might played an important role in the regulation of food intake during fatten and hibernation period.3. We investigated the impacts of food availability on hibernation patterns during the winter. The results show that:The availability of food effects the survivorship of profoundly. The ample energy (fat, food) can reduce the expression of hibernation, thus decrease the physical injury.4. We investigated the differences on the cellular thermogenesis level between the ground squirrels who adopt the different strategy during the winter. The results show that:The thermogenesis in the interbout arousal is relay on the thermogenesis of BAT, and the fuel of thermogenesis is fat tissue. There are differences on the cellular thermogenesis level between the different groups.