ABSTRACT
AIM:To investigate the effects of glucagon-like peptide-1 (GLP-1) receptor agonist exendin-4 on white adipose tissue (WAT) and the underlying mechanisms.METHODS:Male C57BL/6J mice (8 weeks) were chal-lenged by high-fat diet for 12 weeks, and were randomly divided into saline group and exendin-4 group.The mRNA expres-sion of sirtuin 1 (SIRT1), adipose triglyceride lipase (ATGL), TNF-αand adiponectin of WAT was detected by real-time PCR.3T3-L1 adipocytes or mouse embryonic fibroblasts cells were treated with exendin-4 for 24 h.The protein levels of SIRT1, ATGL and hormone-sensitive lipase (HSL) were determined by Western blot.RESULTS:Exendin-4 significantly decreased epididymal fat weight, fasting blood glucose and serum triglyceride levels ( P<0.05) , and reduced body weight and serum TNF-αlevel.The mRNA expression of SIRT1, ATGL and adiponectin in WAT was all significantly up-regulated by exendin-4, which were contrary to the down-regulation of TNF-αmRNA expression (P<0.05).Exendin-4 promoted the protein expression of SIRT1, ATGL, and HSL in 3T3-L1 adipocytes in a dose-dependent manner.Less lipid droplets with up-regulation of lipolytic protein expression were observed when combined with SIRT1 agonist treatment, which were suppressed by SIRT1 inhibitor.Deletion of SIRT1 led to larger adipocytes with more lipid droplets, and the effect of ex-endin-4 on the lipolysis disappeared when SIRT1 was deficient.CONCLUSION:Exendin-4 promotes lipolysis in WAT of obese mice via activation of SIRT1.