| Objective:Sedentary habits are associated with low levels of cardiorespiratory fitness and high risk of all-cause mortality, while physical activity habits are associated with fitness improvements and reduced mortality risk. However, the physiological mechanism of physical activity-induced physical fitness remains only partly understood. As tissue oxygen consumption increases greatly during exercise, it is logical to speculate that reactive oxygen species reactive oxygen species (ROS), the inevitable byproducts of energy metabolism, may involve in the physical fitness. However, the detailed mechanism of ROS improving physical fitness still need further study to explore. Therefore, this study will explore the dynamic process of exercise-induced oxidative stress and the mechanism of its effect on nonalcoholic fatty liver disease (NAFLD) with the help of different treadmill-training programs in rats.Methods:(1)Adult male SD rats (200g-220g,8weeks), after high-intensity exercise, were used for exploring the dynamic processes and mechanisms of exercise-induced oxidative stress;(2) adult male SD rats (220g-250g,8weeks), after a long-term treadmill-training in different intensities, the effects and the mechanisms of exercise on improving NAFLD were explored from biochemical and proteomic analysis.Result:(1) after a single bout of high-intensity treadmill training, the levels of oxidative stress biomarkers in skeletal muscle and liver were significantly increased, and the peak were appeared at the time of the30th minute after exercise. At this time, the levels of MDA, GSH and GST in liver were significantly increased, whether compared with the sedentary control group or the group of sacrificed immediately after exercise. Though the levels of oxidative stress biomarkers in serum were decreased, there was a shoulder peak at the30th minute after exercise. At this moment, the levels of MDA and TAC were significantly lower than those in sedentary control group (P<0.01), but the level of MDA was significantly higher than it in the group of sacrificed immediately after exercise or the group of sacrificed at the60th minute after exercise (P<0.05).(2) After a long-term treadmill-training in different intensities, though there were varieties in the changes of oxidative stress biomarkers in different tissues/organs, the exercise at25m/min seemed to improve oxidative stress in all detected tissues/organs. All exercise programs resulted in decrement of oxidative stress in serum, in the exercise at25m/min accounted for the lowest. As for skeletal muscle, the exercises both at25m/min and35m/min improved oxidative stress significantly, while the exercise at15m/min not. Intriguingly, the exercise at25m/min was responsible for the most effective attenuations in hepatic oxidative stress and fatty liver.(3) The results from Pearson correlation analysis illustrated that the levels of hepatic oxidative stress biomarkers were significantly positive correlated with the levels of intrahepatic triglyceride (IHTG), a well-used biomarker of NAFLD(P<0.01).(4) The proteomic results indicated that a modified biotin-avidin affinity technique was effective in purification and enrichment of carbonylated proteins. With this technique, we had identified a total of30carbonylated proteins,1protein unique to exercise group and11proteins unique to sedentary group. Among the carbonylated proteins unique to sedentary, a long-chain specific acyl-CoA dehydrogenase was a key enzyme that catalyzed the initial step in fatty acid β-oxidation. Further analysis revealed that the enzyme was susceptible to oxidative modification, and it contained8oxidation sites.Conclusion:(1) After high-intensity exercise, the dynamic adaptive mechanism of oxidative stress is one of components of the whole-body adaptive mechanism, and the mechanism of the improvement of oxidative stress induced by long-term training is a mechanism of hormesis.(2) Long-term moderate treadmill training is effective in improving NAFLD as indicated by the levels of IHTG, which is closely related to the amelioration of oxidative stress. Through regulating the activities of the proteins susceptible to oxidative modification, ROS may involve in the mechanism of exercise induced NAFLD improvement.(3) The modified avidin affinity technique is a practical and powerful tool for selecting carbonylated proteins. |
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