Macroautophagy is a major pathway of autophagy in the cells. It plays roles in breaking down of proteins or organelles using lysosomal proteases. This study investigated the effects of chronic exercise training on macroautophagy in skeletal muscles of both adult and older rats. Adult (18 mo) and old (28 mo) male Fischer 344 rats were assigned to either a sedentary control or an endurance training group (n = 6 per group). Animals in the training groups ran on a treadmill for 8 weeks. The training intensity was adjusted to be identical between the adult and old groups. After completing the training program, the soleus and plantaris muscles were taken for subsequent analyses of autophagy-related proteins. In the plantaris muscle, Beclin 1, microtubule-associated protein light chain 3 (LC3) -I and LC3-II were elevated by aging. Aging lowered Atg7 but exercise training restored the Atg7 expression in the plantaris muscle. In the soleus muscle, aging increased only LC3-I. Taken together, the results show that the expression of macroautophagy protein can be altered by both aging and exercise training. Importantly, the manner of alteration is not entirely consistent among examined proteins and muscle types.

DESCENTE SPORTS SCIENCE Vol.31/THE DESCENTE AND ISHIMOTO MEMORIAL FOUNDATION FOR THE PROMOTION SPORTS SCIENCE