The nitric oxide and glutathione response in tissues of trained mice during hyperbaric oxygenation preconditioning and after physical stress

Background There is a controversy about the ability of hyperbaric oxygenation to cause oxidative stress in tissues and the multiple data that hyperbaric oxygen preconditioning (HBOP) show a protective effect against oxidative stress in different types of stress or pathologies, including the response to physical stress observed in our previous studies in trained female mice. Methods Utilizing the same animal model, we have investigated in multiple tissues, the effect of the HBOP on the immediate and 24 hours-recovery responses of the redox state parameters, both at basal levels, during the session, and after physical stress. Results It was observed a reduction in the basal levels of tetrahydrobiopterin, nitric oxide, and catalase during a session of HBOP in most tissues, a decrease in the level of reduced glutathione (GSH) in liver, and at the same time its augment in muscle, and intestinal mucosa, being steady in other tissues. The baseline of the redox state for the experimental group returned to or exceeded levels of the control group during recovery for most of the tissues. GSH and related enzymes remained above control in most tissues both during physical stress and after recovery. Conclusion HBOP causes uncoupling of nitric oxide synthases in tissues with a moderate decrease in nitric oxide production and an increase in superoxide anion generation. Superoxide dismutase converts superoxide anion to peroxide resulting in catalase activity wear. It is probably that the decrease in nitric oxide facilitates GSH redistribution from the liver to other tissues, strengthening its antioxidant defense.