Effects Of Calcium Signal On The Transcription Of GPR120 And Adipogenesis In Mice And 3T3-L1 Preadipocytes

The present research aimed at exploring the effects of calgium signal on the transcription of GPR120 and adipogenesis in vivo and in vitro.To provide theoretical proof for further illustrating the regulation of adipogenisis by GPR120. Kunming mice and 3T3-L1 preadipocytes were the study subjects. The mice were fed with normal rodent diets and were treated with Calglucon and Ca2+-channel antagonist Nifedipine respectively for 30 days. The cultured 3T3-L1 preadipocytes were treated with 5 mmol/L Calglucon injection and 10μmol/L Nifedipine respectively. Body weight, liver mass, subcutaneous fat pads, epididymal fat pads and perirenal fat pads were weithed. Levels of Total cholesterol(TC), triglycerides(TG) and high density lipoproteincholesterol(HDL-C) in serum were measured. Lipase activity in mice liver and adipose tissues was measured by Lipase Activity Test Kit. Real-time PCR was applied to detect the expression levels of GPR120 and adipose metabolism related genes. The expression correlations of GPR120 with adipose metabolsim related genes in mise epididymal fat tissue were analyzed by using SPSS Stastistics Analysis Software. The main results were summarized as follows:1. In calglucon treated group, dietary calglucon can attenuate the increase of body mass and decrease the ratio of body fat to body weight, the concentrations of TG, TC and LDL-C in blood serum were decreased significantly (P<0.01), and the level of HDL-C was increased(P<0.05). Lipase activities in liver and epididymal fat tissues were significantly inhibited by calglucon. The expression levels of GPR120 and FAS mRNA were reduced in mice liver tissue, subcutaneous fat tissue, epididymal fat tissue and perirenal fat tissue. Calglucon inhibited the expression of PPARγmRNA in periepodidumal fat tissue and perirenal fat tissue, and also down regulated the expression of C/EBPαin liver and epididymal fat tissues. By contrast, Nifedipine can increase the deposit of body fat mass and heighten the levels of TG and TC in blood serum. Nifedipine increased the lipase activity in liver, epididymal fat tissue and perirenal fat tissue. The transcription levels of GPR120, FAS, PPARγas well as C/EBPαwere increased in liver, subcutaneous fat, epididymal fat and perirenal fat tissues, meanwhile, in these tissues, the transcriptional levels of HSL were decreased by Nifedipine. It's suggested that Calglucon could decrease serum blood-fat level and inhibit body fat deposit. To some extent, Nifedipine can accelerate the deposit of body fat. 2. The expression correlation analysis results in mice epididymal fat tissue showed that GPR120 correlates with PPARγ, C/EBPαand FAS but not with HSL. It indicated that GPR120 was highly associated with adipogenesis.3.Treat cultured 3T3-L1preadipocyted with 5 mmol/L calglucon injection for 24 h, the content of intracellular lipid was decreased, and the transcripional levels of GPR120, FAS, PPARγand C/EBPαwere down-regulated. When treated with 10μmol/L Nifedipine for 24 h, Nifedipine accelerated the deposition of intracellular lipid, and increased the transcriptional levels of GPR120, PPARγ, C/EBPαand FAS. After 72 h, Calglucon injection significatly increased the deposition of intracellular lipid, and upregulated the expression levels of GPR120, PPARγ, C/EBPαand FAS. It indicats that calcium signal may play a very complicated role in regulating adipogenesis.