Effects of a chronic exercise training protocol on oxidative stress and right ventricular hypertrophy in monocrotaline-treated rats

1. In the present study, we investigated the effects of exercise training on cardiac hypertrophy and oxidative stress in a monocrotaline (MCT)-induced cor pulmonale model. Male Wistar rats were assigned to one of three groups: sedentary control (SC); sedentary MCT (SM); or trained MCT (TM). 2. Right ventricular hypertrophy (RVH) was induced by a single injection of MCT (60 mg/kg, i.p.). Exercise training consisted of running on a treadmill (five times a week, during Weeks 3, 4 and 5). Systemic oxidative stress was evaluated in erythrocytes by chemiluminescence (CL) and the activity of the anti-oxidant enzymes superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and glutathione S-transferase (GST) was determined. 3. At Week 3, MCT-treated animals exhibited RVH, lung congestion, decreased SOD activity and increased CAT activity. Exercise training reduced MCT-induced RVH and increased GST activity. At Week 4, MCT-induced RVH was accompanied by an increase in CL and GST activity. However, in TM animals there was a decrease in CL and augmented SOD activity. At Week 5, there were no survivors in the SM group, whereas GST activity was elevated in TM rats compared with SC rats. There was no difference in GPx activity throughout the experimental protocol between the groups. 4. Taken together, our results indicate that exercise training is able to ameliorate RVH and improve survival, which is associated with a reduction in oxidative stress in MCT-treated rats.