Exercise training enhances cardiac IGFI-R/PI3K/Akt and Bcl-2 family associated pro-survival pathways in streptozotocin-induced diabetic rats

Background Increased myocyte apoptosis in diabetic hearts has been previously reported. The purpose of this study was to evaluate the effects of exercise training on cardiac survival pathways in streptozotocin (STZ)-induced diabetic rats. Methods Forty-eight male Wistar rats were randomly divided into control group (Control), STZ-induced (65mg/kg, i.p.) diabetes (DM), and DM rats with moderate aerobic exercise training (DM-EX) on a treadmill 60min/day, 5days/week, for 10weeks. Histopathological analysis, positive TUNEL assays and Western blotting were performed on the excised cardiac left ventricles from all three groups. Results The components of cardiac survival pathway (insulin-like growth factor I (IGFI), IGFI-receptor (IGFI-R), phosphatidylinositol 3′-kinase (PI3K), and Akt) and the pro-survival Bcl-2 family proteins (Bcl-2, Bcl-xL, and p-BAD) were all significantly decreased in the DM group compared with the Control group whereas they were increased in the DM-EX group. In addition, the abnormal myocardial architecture, enlarged interstitial space and increased cardiac TUNEL-positive apoptotic cells were observed in the DM group, but they were reduced in the DM-EX group. The apoptotic key component, caspase-3, was significantly increased in the DM group relative to the Control group whereas it was decreased in the DM-EX group. Conclusions Exercise training enhances cardiac IGFI-R/PI3K/Akt and Bcl-2 family associated pro-survival pathways, which provides one of the new beneficial effects for exercise training in diabetes.