Exercise is a deterrent of cardiovascular disease and atherosclerosis, but the mechanisms by which exercise reduces atherogenic risk remain unknown. The aim of the present study was to investigate the effects of chronic exercise and/or high cholesterol diet on primary antioxidant enzymes and plasma total antioxidant capacity in Dutch rabbits. Materials and Methods: 60 male Dutch white rabbits were divided into four groups: The normal diet control (NC), normal diet with exercise (NE), high-cholesterol diet control (HC) and high cholesterol diet with exercise (HE). Animals in high cholesterol diet groups were fed 2% cholesterol rabbit chow for 8 weeks. Animals of exercise groups ran on a treadmill at 0.88 km/h for 10 –60 min/day, 5 day/week, and 8 weeks in total. At the end of experiments, blood samples were drawn from vena cavae and were used for determination of Glutathione Peroxidase (GPX), Superoxide Dismutase (SOD) and Catalase (CAT) activities in red cells, plasma Total Antioxidant Capacity (TAC), Malondialdehyde (MDA) and serum cholesterol profile Thoracic aorta and carotid arteries were isolated for histological examination to evaluate atherosclerosis. Results: We found that 8 weeks of chronic exercise reduced atherogenic diet-induced atherosclerotic lesions in all arteries along with positive changes in cholesterol profile especially increase of serum HDL-C level. Plasma MDA and TAC concentrations were enhanced by exercise in the both normal and hypercholesterolemic groups. Erythrocyte catalase activity was increased significantly by chronic exercise (P<0.05), whereas total SOD activity rose with exercise only in the control group. Surprisingly, GPX activity was significantly decreased in response to exercise in the control group and also in the high cholesterol diet group. Conclusion: It is speculated that exercise is an appropriate method for prevention and regression of atherosclerosis that accompanies enhancement of plasma TAC and positive changes in serum cholesterol profile; the exercise effects on red cell antioxidant activities is however more limited in hypercholesterolemic animals as compared to normal ones possibly in part because of alterations in the ability to adapt to exercise– induced oxidative stress in the high cholesterol diet.
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