The Regulation Of Fat Accumulation Medited By Adiponectin

Adipose tissue is not only an energy storage reservoir but also an important endocrine organ in which the metabolism is very active. It can secrete a number of adipocytokines, such as leptin, adiponectin, resistin etc. These adipocytokines can mediate the functions of many organs through autocrine/paracrine, especially regulating insulin resistance and glucose metabolic disorder linking to obesity.Myogenesis is a highly complex and regulated process including cell cycle arrest and muscle specific transcription factor expression. Skeletal muscle has been identified as the major tissue in glucose metabolism. As an important energy source for skeletal muscle, intramyocellular lipid provides the fuel required for mitochondrial fat oxidation during exercise. Increasing evidence suggested that excessive intramyocellular lipid is significantly correlated with insulin resistance. It is very important to study the crosstalk between fat and skeletal muscle for the occurrence of skeletal muscle insulin resistance.Adiponectin is newly discovered hormones specially secreted from adipocytes. Adiponectin circulates in blood in multiples such as trimers, hexamers and a high molecular mass species. The globular adiponectin exists independently in vivo and has the similar functions to the full-length adiponectin. Adiponectin can stimulate the fatty acid oxidation in skeletal muscle, decrease plasma triglyceride, and improve glucose metabolism by increasing insulin sensitivity.In this study, by using real-time PCR, transfection, we studied intramyocellular lipid accumulation during the myogenesis, the effects of adiponectin on this process, follicle-stimulating hormone regulate the expression of AdipoR1, and the cloning and biological characteristics of pig APPL1 and APPL2, and got the following results:1. Using C2C12 myoblasts as the model, add 2% horse serum as a differentiation medium, we studied the intramyocellular lipid accumulation during the myogenesis by oil red O staining, we found that the intramyocellular lipid markedly decreased during C2C12 differentiation.2. Studied the expression pattern of lipid and glucose metabolism related genes and adiponectin receptor related genes during the C2C12 myogenesis by Real- Time PCR, and we demonstrated that lipid accumulation in C2C12 cells is rapidly reduced during myogenesis, apparently due to increased fatty acid oxidation and decreased fatty acid synthesis. And we also found the correlation between myogenesis and dynamic expression of adiponectin receptors.3. We demonstrated that adiponectin reduces intramyocellular lipid accumulation through promoting fatty acid oxidation, rather than hydrolysis and synthesis, during C2C12 differentiation.4. By the comparative analysis, according human APPL1 and APPL2 sequences, pig APPL1 and APPL2 genes were cloned. By Real-Time PCR, the tissue expression profiles of APPL1 and APPL2 in ten tissue samples were determined. By chromosome electronic positioning analysis, pig APPL1 and APPL2 were located.5. Stimulated with recombinant human follicle-stimulating hormone on 3T3-L1 cells and C2C12 cells in vitro, we found that FSH can increase the expression level of AdipoR1 mRNA at concentration of 5ng/ml by Real-Time PCR. However, FSH has the opposite effect on the expression of AdipoR1 on NIH3T3 cells.