Gender differences in nitric oxide and antioxidant response to physical stress in tissues of trained mice

Introduction: Nitric oxide (NO) is an important regulator involved in functional adaptation in all tissues to exercise, as shown in recent studies. The aim of this shortterm study was to evaluate the hypothesis that the important factor of higher performance of trained females during exhaustive exercise can be the interaction between physiological effect of nitric oxide and oxidant/antioxidant response. Methods: Males and females of trained mice were divided into three groups: basal, fasting and prolonged exercise. Parameters of oxidant/antioxidant state, including nitric oxide and glutathione were measured in blood, muscle, liver, heart, kidney, brain, small intestine, adipose tissue and thoracic aorta. Females in this animal model had better performance than males during exhaustive exercise. Results: Females showed greater basal levels of nitric oxide, total antioxidant status and glutathione peroxidase in most tissues evaluated. Compared to fasting levels, the net effects of prolonged exercise included lipoperoxidation in liver, brain and kidney, and nitrosative stress in liver, muscle and heart only in males. The decrement of glutathione without significant changes in its grade of oxidation was observed in liver, intestine and adipose tissue only in females, confirmed possible redistribution of reduced glutathione during prolonged exercise. Conclusion: It is possible that the gender difference that existed in the performance of the animals during exhaustive exercise was determined by NO modulation of the oxidant/antioxidant response in tissues, and particularly of the redistribution of glutathione from the liver to other tissues. NO- induced vasodilatation can be beneficial for ischemic tissues during prolonged or exhaustive exercise.