Effects of Heavy Load Exercise and Acupuncture on Mitophagy in Rat Skeletal Muscle: 2784 Board #304 June 2 9

PURPOSE: To examine the effects of heavy load exercise and acupuncture on mitochondrial structure and mitophagy in rat skeletal muscle. METHODS: Male Sprague-Dawley rats were divided into 4 groups: control group (C, n=40), exercise group (E, n=40), acupuncture group (A, n=40), exercise and acupuncture group (EA, n=40). Rats in the E and EA groups ran on a rodent treadmill down a 16°grade at 16m/min for 90 min, and those in the A and EA groups received a 2-min session of acupuncture (needing of the bilateral soleus muscle). Each group was further divided into 0h,12h,24h,48h and 72h sub-groups (n=8 each), and at each time point the bilateral soleus muscle was collected under anesthesia. Mitochondrial ultrastructural changes in skeletal muscle were observed by a transmission electron microscope. The content of quatitative enzyme citrate synthase (CS) was measured by ELISA. Protein expression of PTEN-induced putative kinase 1 (PINK1), mitochondrial Parkin, microtubule-associated protein 1 light chain 3 (LC3) were determined by western blot. Mitochondrial co-localization with Parkin and LC3 was measured by the immunofluorescence double labeling technique. The data of variables were all analyzed by one-way or multivariate ANOVA. RESULTS: After heavy load exercise, the mitochondrial structure appeared to be abnormal and formed a large number of mitophagosomes; the CS content decreased 25.8%-50.1%; the expression of PINK1 (E12=2.552±0.141),Parkin (E24=2.535±0.100),LC3 (E12=2.757±0.180) significantly increased (C=1.000, p<0.05 to p<0.01). Acupuncture promoted the recovery of mitochondrial ultrastructure, alleviated the reduction of CS content, and lowered the expression of PINK1 (EA12=1.738±0.083),Parkin (EA24=2.053±0.117),LC3 (EA12=1.718±0.095) in mitochondria (C=1.000, p<0.05). CONCLUSION: Heavy load exercise may activate the PINK1/Parkin pathway, promote the combination of LC3 and mitochondria, and result in mitophagy and mitochondrial damage within skeletal muscle. Acupuncture can decrease the expression of PINK1 and Parkin, and inhibit the combination of LC3 and mitochondria, thereby inhibiting excessive activation of mitophagy and alleviating mitochondrial damage within rat skeletal muscle.(Supported by Sports Medicine key laboratory of Sichuan province Foudation).