Long term dietary restriction ameliorates swimming exercise-induced oxidative stress in brain and lung of middle-aged rat.

Exhaustive exercise may generate oxidative stress in brain and reported findings are conflicting. Long term dietary restriction (DR) may be useful in the inhibiting of free oxygen radicals generated during exhaustive exercise in the brain of rat. Hence, in this study we evaluated beneficial effects of long term DR on the oxidative stress and antioxidant enzyme systems in brain cortex and lung in rats after different intensities of swimming exercise. Sprague-Dawley rats (60) were assigned as DR and ad libitum (AL) groups, and each group was further subdivided into three groups namely control (sedentery), submaximal exercise (endurance exercise) and maximal exercise (exhaustive swimming exercise) groups. Animals in the endurance exercise group swam 5 days/week for 8 weeks while exhaustive swimming group was subjected to an acute bout of exercise. With the increase in intensity of exercise, degree of lipid peroxidation (LP) and protein oxidation (PO) were also increased in DR and AL groups; however rate of increase was lower in DR group than AL group. Glutathione (GSH) and glutathione peroxidase (GSH-Px) activity were lower but glutathione reductase (GR) activity was higher in DR group compared to AL group in endurance and exhaustive swimming exercise. With increase in exercise intensity, GSH and GR enzyme activity decreased, whereas an increase was observed in GSH-Px enzyme activity. There was no difference in LP, PO, GSH and GR activity between DR and AL groups. GSH-Px activity in brain cortex was significantly lower in DR group than in AL group and sedentary rats. Results indicate that long term dietary restriction may protect against endurance and exhaustive swimming exercise-induced oxidative stress in rats by inhibiting oxidative stress.