Liraglutide ameliorates non‐alcoholic fatty liver disease by enhancing mitochondrial architecture and promoting autophagy through the SIRT1/SIRT3–FOXO3a pathway. Issue 9 (11th January 2016) - Tong, Wenxin
Abstract : Aim: Overwhelming oxidative stress is implicated as crucial in the pathogenesis of non‐alcoholic fatty liver disease (NAFLD). Liraglutide, a well‐established antidiabetes drug, was recently reported to ameliorate NAFLD with an elusive mechanism. We used a mouse model to examine whether liraglutide could ameliorate NAFLD and explored the possible mechanisms. Methods: Twenty C57BL/6J mice were randomly treated with a normal‐fat diet or high‐fat diet for 16 weeks, then further distributed into four groups and subjected to s.c. injection of liraglutide or saline for 4 weeks. The growth/metabolism, oxidative stress, mitochondrial architecture and autophagy were assessed prospectively at the 20th week. Results: High‐fat diet inducement resulted in severe NAFLD while liraglutide treatment significantly reversed the trend, marked by reduced bodyweight, improved glucose tolerance and liver triglyceride composition. Reduced hepatic malondialdehyde level, increased mRNA and protein levels of CATALASE and MNSOD indicated liraglutide affected both the oxidative and antioxidative process to ameliorate oxidative stress. After liraglutide administration, the upregulated mRNA and protein levels of mitochondrial fission and fusion‐related DRP1, OPA1 and respiratory chain‐related COMPLEX1, UCP2 demonstrated the enhancement of mitochondrial architecture which may attenuate the generation of reactive oxygen species (ROS), while the diminished mRNA and protein level of P62 and increased levels of Beclin1 and LC3II/I ratio indicated the promoting autophagy, which probably contribute to the ROS elimination. Further, restored protein levels of Sirtuin1/Sirtuin3 and the downstream p‐FOXO3a reveal the probable pathways of liraglutide acting on autophagy. Conclusion: Liraglutide diminishes oxidative stress by enhancing mitochondrial architecture and promoting autophagy through the SIRT1/SIRT3–FOXO3a–LC3 pathway to ameliorate diet‐induced NAFLD.