Oxidative stress in skeletal muscle exercise and injury

运动是延长人类健康寿命的有力干预措施，被广泛提倡预防老年功能衰退。锻炼可以增加肌肉量，防止虚弱，增加活动能力，从而提高生活质量。长期以来，氧化应激一直被视为运动的负面影响，但最近的研究结果表明，减少氧化应激可能会阻碍运动的有益效果。利用在线粒体或细胞质中表达比例氧化还原敏感荧光蛋白（roGFP1）的转基因小鼠，我们使用体内共聚焦成像技术记录了活体动物骨骼肌的细胞氧化还原状态。单独激活完整肌肉不会引起肌肉细胞质或线粒体氧化还原状态的任何变化，但在一个偶然的发现中，电刺激确实诱导了单个受伤肌肉纤维周围肌肉纤维的氧化应激。肌肉纤维损伤是运动中常见的现象，被视为肌肉剧烈活动的负面后果。我们的研究结果表明，肌纤维损伤可能在介导氧化还原信号中起重要作用，而氧化还原信号是运动有益效果所必需的。我们初步得出结论，损伤肌纤维释放的危险相关分子模式（DAMPs）与肌肉激活一起导致邻近组织肌纤维中观察到的氧化还原瞬态。我们的发现解决了许多关于氧化应激和肌肉损伤在运动益处中的作用的相互矛盾的观察结果。

Exercise is a powerful intervention to increase health span in humans and widely advocated to prevent the functional decline occurring in old age. Exercise builds muscle mass, which prevents frailty, increases mobility, as a consequence, quality of life. Oxidative stress has long been seen as a negative consequence of exercise, but recent results suggest that reducing oxidative stress can prevent the beneficial effects of exercise. Using transgenic mice expressing a ratiometric redox-sensitive fluorescent protein (roGFP1) in mitochondrial or cytosol, we recorded the cellular redox state in skeletal muscle of live animals using in vivo confocal imaging.Activation of intact muscle alone did not cause any changes in the redox state of cytosol or mitochondria of muscle, but in a serendipitous discovery, electrical stimulation did induce oxidative stress in muscle fibers surrounding a single injured muscle fiber. Muscle fiber injury is a common occurrence in exercise, and seen as negative consequence of strenuous muscle activation. Our results indicate that muscle fiber injury probably plays an important role in mediating the redox signaling necessary for the beneficial effects of exercise. We tentatively conclude that danger associated molecular patterns (DAMPs) released by injured muscle fibers cause, together with muscle activation, the observed redox transients in adjacent tissue muscle fibers. Our findings resolve many conflicting observations concerning the role of oxidative stress and muscle injury in the benefits of exercise.