Abstract: Objective: To explore the effect of aerobic exercise on the changes of autophagy in skeletal muscle cells in rats with insulin resistance and the expression of autophagy-related protein. Methods: Thirty-six male SD rats were randomly divided into three groups: Normal Diet group (ND, n=12), High Fat Diet group (HFD, n=12) and High Fat Diet + Exercise intervention group (HFD + EXE, n=12). Rats of HFD and HFD + EXE group were fed high fat diet in the whole experiment. Swimming was used for aerobic exercise intervention, 60min per day, six days per week, and the intervention lasted 8 weeks. The autophagosome was observed by transmission electron microscope in gastrocnemius muscle, and the expression of LC3-I、LC3-II、LC3-II/LC3-I and Beclin-1 were tested by Western blot. Results: Compared with ND group, fasting blood glucose and HOMA-IR of HFD group increased significantly. After exercise intervention, both the FBG and HOMA-IR in HFD+EXE group had a downward trend. In the ultrastructure, the mitochondria of the HFD group showed obvious damage, and some mitochondria were vacuoles. Conclusion: Aerobic exercise can increase the autophagy level of skeletal muscle cells of insulin resistance rats induced by high-fat diet, and protect skeletal muscle cells. Mitochondrial injury in HFD+EXE group was significantly improved, but no autophagy was found in each group. Compared with ND group, LC3-II, Beclin1 and LC3-II/LC3-I in HFD group decreased significantly. The tendency of LC3-II, LC3-II/LC3-I and Beclin1 increased after exercise intervention.

Key words: aerobic exercise, insulin resistance, skeletal muscle, autophagy