The effects of exercise on the oxidant-antioxidant balance in rat brain.

ABSTRACTThe Effects Of Exercise On The Oxidant-Antioxidant Balance In Rat Brain.lkay AksuIt is known that exercise has a positive effect on many systems. Acute exercise causesoxidant stress by creating an unbalanced status between oxidant and antioxidant levels by acuteexercise. It is also known that exercise strengthens antioxidant defense. There is little evidencethat exercise causes oxidant stress in brain. In this study, different intensity of acute and chronicexercise were applied and it was intended to reveal the effect of acute and chronic treadmillexercise on the oxidant-antioxidant equilibrium, in the prefrontal cortex and striatum where thedopamimergic neurons end and in the hippocampus, the target region of the glucocorticoids.In this study, 22-week old Sprague Dawley rats were used. Rats were run on treadmill for1 hour a day on speeds 10 m/min, 15 m/min, 20 m/min consequently and 25 m/min against 5degree inclination upwards until exhaustion. In chronic exercise groups, they were run ontreadmill for 1 hour a day on speeds 10 m/min, 15 m/min, 20 m/min consequently, 5 days a weekfor 8 weeks. In acute and chronic exercise experiments, two control groups were used. The firstcontrol group was the non-handled group which the rats were not exposed to handling stress.The second control group included the rats which were put on the treadmill without being forcedto run. Hippocampus, prefrontal cortex and striatum regions were extracted and the superoxidedismutase, glutathione preoxidase enzyme activity, nitrite-nitrate levels and the levels of thesubstances that react with thiobarbituric acid were measured. Results were interpreted byKruskal-Wallis one-way variance analysis using SPSS software.In none of these three regions of the brain, glutathione preoxidase, substances that reactwith thiobarbituric acid and nitrite-nitrate levels were found to be effected by acute exercise butsuperoxide dismutase enzyme activity in striatum was found to be increased in the chronic 20m/min group. By chronic exercise, levels of substances that react with thiobarbituric acid andnitrite-nitrate were not found to be effected, superoxide dismutase enzyme activity in thehippocampus was found to be decreased in the group of 10-15 m/min running speed andglutathione preoxidase activity in the prefrontal cortex were found to be increased in the handledgroup -exposed to the handling stress- compared to the control group. In conclusion, neitheracute nor chronic exercise were found to cause oxidant stress in prefrontal cortex, striatum andhippocampus, but chronic exercise was found to have a probable positive effect on oxidant stressby decreasing the formation of superoxide radicals.Key words: exercise, oxidant stress, prefrontal cortex, striatum, hippocampus, treadmill exercise.7