ABSTRACT
Objective To explore the effects of an aerobic exercise of different durations on the binding capacity of NF-E2-related factor 2(Nrf2)/Kelch-like ECH-associated protein-1(Keap1) in skeletal muscle of mice.Methods Thirty C57BL/6J mice were divided into a control(0h) group,an acute exercise for 3 hours (3h) group and an acute exercise for 6 hours(6h) group.The mice ran on treadmill at the speed of 15 m/min for different durations.The mice were sacrificed immediately after exercise and collected skeletal muscles of legs.The high quality fluorescence assay was done to detect the reactive oxygen species(ROS) level in the skeletal muscles of mice.The binding capacity of Nrf2/Keap1 was detected using co-immunoprecipitation.The expression of Nrf2 and Keap1 was analyzed using the Western blotting.Result Compared with group 0h,the Nrf2/Keap1 binding capacity in skeletal muscles of group 3h and 6h decreased significantly(P＜0.05),but the total Nrf2 in skeletal muscles increased significantly(P＜0.05).No significant differences were observed in the expression of total Keapl.The expression of Nrf2 protein of group 3h and 6h increased significantly compared with 0h,with that of group 6h significantly higher than group 3h(P＜0.05).The ROS level in skeletal muscles of group 6h increased significantly compared with group 0h(P＜0.05).Conclusion The effect of acute aerobic exercise on Nrf2/Keap1 binding capacity in skeletal muscle of mice depends on its duration.
ABSTRACT
Objective To explore the effects of different weeks of high intensity interval training (HIIT) and moderate intensity aerobic exercise on maximal oxygen uptake (VO2max) and the expression of the skeletal muscle oxidative capacity related factor AMP-activated protein kinase (AMPK) and peroxisome proliferators γactivated receptor coativator-1-α (PGC-1α),so as to provide the basis for the choice of effective load intensity.Methods One hundred and twenty 6-week-old SPF male Wistar rats were equally randomized into 3 groups according to their body weight:a sedentary control group (not receiving any exercise),a moderate-intensity exercise group (undergoing 50-min continuous running at an intensity of 60％-70％ VO2max) and a HIIT group (conducting 3-min running at 90％ VO2max interspersed with 3-min recovery periods at 50％ VO2max and repeating that process 6 times,with a 7-min warm-up and cool-down period at 70％ VO2max).All rats except those in the control group exercised five days a week and 50min per day.All rats were measured their weight at 8:00-9:00am every Sunday.Soleus was taken from ten randomly chosen rats of each group at 2nd,4th,6th and 10th week after the onset of the intervention.The VO2max test was done before taking muscles.Western blotting was used to detect the protein expression of AMPK and PGC-1α.Results (1) Both the exercise duration and mode had a significant impact on rats' body weight,and they had interaction with each other (P＜0.01).(2) The average PGC-1α expression in the skeletal muscle of 10-week HIIT group were significantly higher than those in the control group (P＜0.05),and the average VO2max at the same time was also significantly higher than the other two groups.(3) In the HIIT group,the average VO2max at the 10th week was significantly higher than that at the 2nd,4th and 6th week (P＜ 0.05).The average protein expression of AMPK in the skeletal muscle at the 4th week in the moderate-intensity exercise group was significantly higher than that at the 2nd and 6th week of the same group,and that at the 2nd week of the control group (P＜0.05).The average protein expression of PGC-1α in the HIIT group from the 2nd to the 10th week was significantly higher than the control group at the 2nd week (P＜0.05).(4)The protein expression of PGC-1α was significantly correlated with temporal variation of VO2max in the HIIT group (P＜0.05).Conclusion Ten-week HIIT can effectively promote the expression of AMPK and PGC-1α in skeletal muscles and the maximal oxygen uptake.It plays a more quick and effective role in improving oxidant capacity and cardiorespiratory endurance of skeletal muscles than traditional moderate-intensity exercises.