Introduction & Objective: Diabetes is a metabolic disorder caused by low secretion or resistance to the insulin action. Oxidative stress, as a result of imbalance between the free radical production and antioxidant defense systems is strongly related to diabetes and its complications. The aim of the present study is to evaluate the effect of experimental diabetes and forced treadmill exercise on oxidative stress indexes in heart tissue.

Materials & Methods: 40 male wistar rats (200±20g) were divided into four groups(n=10): control, control with exercise, diabetic, diabetic with exercise. Diabetes was induced by a single dose injection of streptozotocin (50 mg/Kg-1, i.p). Treadmill was performed for 1 hour, 5 days in 8 weeks. At the end of the experiments, the rats were anesthetized by sodium pentobarbital (50 mg/Kg-1, i.p) and left ventricle dissociate from heart and maintenance in -80 ºC. Supernatant from homogenization were used to determine the superoxide dismutase (SOD), gluthatione peroxidase (GPX), gluthatione reductase (GR) and catalase (CAT) activities as enzymatic antioxidant status. Also Maolnyldealdehyde (MDA) level as index of lipid peroxidation and total glutathione (T.GSH) of the heart tissue were measured.

Results: Diabetes significantly reduced CAT and GR activities in diabetic rats compared with control rats. SOD and GPX activities weren't changed in the hearts of the diabetic rats. MDA level, as a lipid peroxidation index, increased in non exercised diabetic rats. In response to exercise, MDA level, CAT, GR and SOD activities showed a significant increase in exercise diabetic rats compared with non exercise diabetic rats.

Conclusion: Forced treadmill with moderate severity has harmful effects on cardiovascular system in diabetes because it increases MDA level of heart tissue in exercised diabetic rats.