Swimming exercise regulates indices of skeletal muscle glucose metabolism and attenuates cardiac inflammatory cytokines activity via IL-6/TNF-α pathway in streptozotocin-induced diabetic rats

Abstract

Diabetes mellitus (DM) manifests with impaired glucose metabolism that affects the musculoskeletal and cardiovascular systems. This study investigated the effects of swimming exercise on some indices of muscle glucose metabolism and cardiac inflammatory markers in diabetic rats induced with streptozotocin. Wistar rats of both sexes (150–200 g) were assigned into five groups of seven (7) rats. Group 1: Control (CON), Group 2: Diabetes only (DM), Group 3: Exercise only (EX), Group 4: Diabetes + Exercise (DM + EX), Group 5: Diabetes + Insulin (DM + IN). Type 1 DM was induced via intraperitoneal injection of streptozotocin (60 mg/kg). Insulin (6 IU/g) was administered (IP) to animals in group 5. Swimming exercise test was done for 27 days after which animals were euthanized. Blood samples were collected while hamstring muscles and heart were harvested and homogenized to assess biochemical parameters. The body weight, serum insulin level, muscle glucose metabolic indices (glycogen, Glut-4, CK-MB), and cardiac troponin-T were significantly (P < 0.05) decreased. In contrast, the random blood glucose, cardiac TNF-α, and IL-6 levels were increased (P < 0.05) in diabetic rats when compared with the control group. Swimming exercise regimen significantly (P < 0.05) reversed these anomalies by reducing blood glucose and cardiac inflammatory cytokines (TNF-α and IL-6) levels, improving serum insulin, muscle glycogen, and GLUT-4 expression in diabetic rats when compared to the DM group. The cardiac inflammatory cytokine levels in DM + EX were comparable to the DM + IN group. In conclusion, swimming exercise improves muscle glucose metabolism and protects the heart against cardiac inflammation in diabetic conditions.