Alpha-lipoic Acid Attenuates Exercise-induced Oxidative Stress And Enhances Heat Shock Protein Responses

Abstract

Uncontrolled oxidative stress, a state where the increased production of ROS overwhelms endogenous antioxidant protection, may result in macromolecular damage and perturbation of redox control of signalling and cellular events. The heat shock proteins (HSPs) respond to a wide variety of stress, including oxidative stress. HSPs function primarily as molecular chaperones, but also control protein synthesis and trafficking, as well as regulate cellular adaptation and survival. PURPOSE: Several antioxidant supplementation strategies have been used to cope with exercise-induced oxidative stress and to facilitate adaptations to exercise. While antioxidant supplementation diminishes exercise-induced oxidative stress, there is also a risk of decreasing the normal response of tissues to exercise and blunting the adaptations. In this study we examined the protective role of natural thiol antioxidant, alpha-lipoic acid (LA) supplementation at rest, after exercise and at different recovery points in skeletal muscle in horses. METHODS: Six standardbred trotters were examined on the treadmill and exercised 75 min at individually defined aerobic level. Blood and muscle biopsy samples were taken before and immediately after treadmill exercise, as well as after 2-, 6-, 24- and 48-hour recovery. RESULTS: LA supplementation (25 mg kg-1 day-1) for five weeks increased the resting levels of HSP90 and the recovery levels of inducible HSP70 in gluteus medius muscle. In addition, following LA-supplementation, we observed a significant decrease in exercise-induced protein oxidation in plasma and free radical formation in muscle, measured by EPR signals. CONCLUSION: Our findings suggest that LA enhances HSP levels and decreases exercise-induced oxidative stress in skeletal muscle.