Mitochondrial Fusion and Fission in Long-term Aerobic Exercise Preventing High-Fat-Diet Induced Insulin Resistance

Abstract

PURPOSE: To explore the effects of mitochondrial fusion and fission in the mechanism of long-term aerobic exercise preventing insulin resistance induced by high fat diet. METHODS: 32 Wistar rats were randomly divided into normal chow diet control group (NC), normal chow plus exercise group (NE), high fat diet control group (HC) and high fat diet plus exercise group (HE). The rats of exercise groups were trained with treadmill 60 min per day at the intensity of 64%VO2max, five days per week for 12 weeks. Rats' Skeletal muscle proteins mitochondrial fusion 2 (MFN2), FIS1, Cytochrome c oxidease subunit IV (COX IV), peroxisome proliferator activated receptor coactivator-1 (PGC-1a), estrogen-related receptor a (ERRa), and Glucose Transporter4 (GLUT4) were determined by western blot. RESULTS: Skeletal muscle MFN2 protein increased by 7.32% in NE group comparing to NC group (P<0.05); increased by 8.54% in HC group comparing to NC group(P<0.05). FIS1 protein increased in HC group by 16.07% comparing to NC group (P<0.05); in HE group increased by 24.62% comparing to quiet high-fat diet HC group(P<0.01). PGC-1a protein expression in skeletal muscle: PGC-1a protein expression in skeletal muscle increased by 61.45% in NE group comparing to NC group(P<0.05) and increased by 10.89% in HE group comparing to HC group(P<0.01). GLUT4 protein expression in skeletal muscle: GLUT4 protein expression increased by 10.80% in NE group comparing to NC group(P<0.05)and increased by 19.76% in HE group comparing to HC group(P<0.01); while decreased by 21.60% in HC group comparing to NC group(P<0.01); COX IV protein expression in skeletal muscle: COX IV protein expression increased by 46.32% in NE group comparing to NC group(P<0.05); and also increased by 53.75% in HE group comparing to HC group(P<0.05). CONCLUSIONS: 12 weeks aerobic training can enhance skeletal muscle mitochondrial fission events and biosynthesis. It seems that long term aerobic training can retrieve the high-fat diet induced impairment by increasing the number of mitochondria and improving glucose transportation in skeletal muscle.