Effect And Mechanism Of Metformin On Liver Lipid Metabolism Disorder In Type 2 Diabetes Mice

Objective Cardiovascular disease caused by abnormal lipid metabolism has become the main cause of death in type 2 diabetes mellitus（T2DM）.Therefore,in the clinical treatment of T2 DM,we should not only focus on the hypoglycemic effect,but also pay attention to the regulation of drugs on lipid metabolism.Metformin is a first-line hypoglycemic drug.After years of clinical applicaton,it has been proved to be beneficial to the blood lipid and liver lipid of T2 DM patients.But at present,the lipid-lowering mechanism of metformin is still uncertain.Therefore,this study aims to explore the possible mechanism of metformin regulating lipid metabolism and provide a strong basis for its clinical application.Methods In this study,we investigated the regulatory effect of metformin on liver lipid metabolism and its possible molecular mechanism in db/db mice and Mc A-Rh7777 cells.The research methods are as follows :（1）In vivo,the effect of metformin on liver lipid metabolism and the expression of WDR12.Grouping: control group,treatment group（Met）.The control group included normal control group（NC）and diabetic control group（DM）.In the treatment group,the dose of metformin was 280 ㎎/㎏·day,the intervention time was 12 weeks,and the control group was given normal saline.During the intervention period,the changes of blood glucose and body weight of mice were measured and recorded.After the intervention,serum and liver samples were collected,and the liver weight of the mice in each group was weighed.The liver sections were stained with H＆E and red O to observe the pathological changes of the livers.The blood lipids and hepatic lipids were detected by biochemical detection kit,and the expressions of lipid synthesis-related proteins and WDR12 in the liver were detected by Western blot.（2）Effects of metformin on lipid metabolism in vivo.Mc A-rh7777 cells were cultured in high glucose medium and treated with different concentractions of metformin（0,0.5,1,1.5,2,3 m M）for 24 hours.The contents of TC and TG in cells and culture medium were detected by kit,and the expression level of lipid synthesis related proteins was detected by Western blot.（3）The expression of WDR12 in vitro and in vivo and the effect of metformin on its expression.The expression of WDR12 in liver and cells treated with metformin was detected by western blot.（4）The possible mechanism of WDR12 regulating lipid synthesis and its effect on AMPK phosphorylation.In Mc A-rh7777 cells,WDR12 si RNA and WDR12 plasmids were transfected respectively,and then the expression levels of proteins related to lipid synthesis were detected in the state of konckdown and overexpression of WDR12,to prove the lipid-lowering effect of WDR12 at the cellular level and explore its lipid-lowering mechanism.Results Animal experimental results showed that the levels of blood lipids and liver lipids in db/db mice were significantly higher than those in C57 mice.Meanwhile,there were obvious fat vacuoles and lipid deposition in liver pathological sections,and the expression levels of proteins related to lipid metabolism such as SREBP1 c,SREBP2,HMGCR and FAS were also significantly increased.After treated with metformin,the levels of serum lipids and liver lipids in mice decreased,and the pathological state of liver was relieved.Compared with T2 DM mice,the expression of lipid metabolism related proteins decreased significantly.The results of cell experiment also showed that metformin could reduce the contents of TC and TG in cells and culture medium and the expression of proteins related to lipid synthesis in cells.Meanwhile,the results in vivo and in vitro showed that metformin can reduce the expression of WDR12.The study of molecular mechanism in cells showed that silencing WDR12 could increase the phosphorylation level of AMPK and inhibit the expression of proteins related to lipid synthesis.Overexpression of WDR12 can inhibit the activation of AMPK and promote the expression of proteins related to lipid synthesis.Conclusion Metformin may regulate the activation of AMPK signaling pathway by down-regulating WDR12,thereby inhibiting the expression of proteins related to lipid synthesis,thereby alleviating the lipid metabolism disorders of T2 DM.