Background. Myocardial fibrosis is identified as a major side effect of Diabetes Mellitus on the heart. Some biomarkers including the ratio of matrix metalloproteinases and their inhibitors in collagen synthesis and collagen degradation are clinically useful in the diagnosis and identification of myocardial fibrosis. In addition, regular aerobic exercise training is one of the major and non-pharmacological solutions for preserving and promoting cardiovascular health. Objectives. Thus, the current research aims at investigating the effect of aerobic training on levels of matrix metalloproteinase-9 (MMP-9) and tissue inhibitor of matrix metalloproteinase 1 (TIMP1) in diabetic rats. Methods. 30 male Wistar rats were randomly divided into 3 groups (healthy control, diabetic control, and exercise diabetic). Diabetes was induced by intraperitoneal injection of streptozotocin at 55 mg/kg per body weight. The exercise program comprised eight weeks of running on a bar for 60 minutes at a speed of 25 m/min. Biopsy was carried out 48 h after the last exercise session, and cardiac levels of MMP-9 and TIMP-1 values were measured by the ELISA sandwich method. Results. The findings of the current research indicated that diabetes induction caused significant increase in cardiac levels of MMP-9 and significant reduction of TIMP-1 compared to the healthy group. In addition, it was revealed that the implementation of 8 weeks-aerobic exercise significantly reduced cardiac levels of MMP-9 and significantly increased TIMP-1 compared to the group without exercise. Conclusions. The execution of aerobic training in diabetic rats inhibited progressive factors of myocardial fibrosis and thus fibrosis risk in diabetic heart is highly reduced.
