KLF15/mTOR related proteins involved in effect of aerobic interval training on improving skeletal muscle lesions in rats with type 2 diabetes

Abstract

Objective: To investigate the effects of aerobic intermittent exercise on the expressions of KLF15/mTOR related proteins to improve skeletal muscle lesions in type 2 diabetes rats. Methods: The experimental model of type 2 diabetes rats was established by feeding high-fat diet for 4 weeks and intraperitoneal injection of streptozotocin (STZ). After modeling, rats were randomly divided into two groups: diabetes model group (DM), diabetes+exercise group (DE), and normal rats were set as control group (C), 10 rats in each group. Group DE was given 8-week aerobic intermittent treadmill exercise intervention, while group C was not given any intervention. At the end of the experiment, the expressions of KLF15, mTOR, p-mTOR, and cleared caspase-3 in gastrocnemius muscle were detected by Western blot. The histopathologic changes of gastrocnemius were observed under microscope; skeletal muscle cells apoptosis rates and muscle mass were examined respectively using HE staining and TUNEL fluorescence staining. At the same time, changes of blood glucose and serum insulin, and weight were examined in the end of the experiment. Results: ①Compared with group C, the wet weight of gastrocnemius muscle and body weight, ratio of wet gastrocnemius muscle and body weight in group DM were decreased(P＜0.05 or P＜0.01); compared with group DM, the wet weight of gastrocnemius muscle, ratio of wet gastrocnemius muscle and body weight in the group DE were increased significantly (P＜0.05). ②Compared with group C, the fasting blood glucose level of group DM was increased significantly (P＜0.01), while serum insulin level of the group DM was decreased significantly(P＜0.01);compared with group DM, the above indexes were opposite in the group DE with intervention(P＜0.05). ③Compared with group C, the morphology of skeletal muscle cells in group DM was abnormal, the number of muscle nuclei was increased, the transverse lines were blurred and disappeared, the sarcomere was broken, and some muscle fibers were dissolved. Compared with group DM, the abnormal cell morphology, segmental injury of sarcomere and dissolution of muscle fibers in group DE were improved. The sarcolemma was more complete and the arrangement of muscle nuclei was more orderly. ④Compared with group C, the expressions of KLF15 and cleaved caspase-3, cells apoptosis rates in group DM were increased significantly(P＜0.01), while p-mTOR/mTOR level was decreased(P＜0.01) ; compared with group DM, the above indexes were opposite in the group with intervention(P＜0.05 or P＜0.01). Conclusion: Aerobic intermittent exercise is beneficial to improve the skeletal muscle pathological changes in type 2 diabetes rats, which may be due to the effective regulation of KLF15/mTOR related protein expression and the reduction of apoptosis damage.