低氧联合运动对大鼠骨骼肌线粒体自噬的影响

Effects of hypoxia combined with exercise training on mitochondrial autophagy in skeletal muscle of rats

目的:观察慢性低氧及低氧联合运动对骨骼肌线粒体自噬的影响,并探讨低氧诱导因子-1α(HIF-1α)在其中的作用。方法:56只健康雄性SD大鼠随机分为:常氧对照组(NC)、低氧对照组(HC)、低氧联合运动组(HT,n=8)、低氧+二甲基亚砜(DMSO)组(HC+D)、低氧+HIF-1α抑制剂YC-1组(HC+Y)、低氧联合运动+DMSO组(HT+D)和低氧联合运动+HIF-1α抑制剂YC-1组(HT+Y)。低氧干预为常压低氧帐篷,模拟11.3%氧浓度。运动干预为低氧帐篷内53%VO2max跑台训练,1h/d。HIF-1α抑制剂组采用YC-1腹腔注射,4mg/kg,1次/d。DMSO组注射等体积1%DMSO。上述干预均持续4周。结果:HC组与NC组比较,线粒体膜电位、ATP合成活力显著降低(P<0.05),活性氧族(ROS)生成速率、PINK1、Parkin、Bnip3和HIF-1α蛋白表达显著升高(P<0.05)。HT组与HC组比较,线粒体膜电位、ATP合成活力、Parkin、Bnip3和HIF-1α表达显著升高(P<0.05),ROS生成速率和PINK1表达显著降低(P<0.05)。YC-1干预HC和HT组,均造成线粒体膜电位、ATP合成活力、Bnip3和HIF-1α表达显著降低(P<0.05),ROS生成速率和PINK1表达显著升高(P<0.05)。结论:低氧联合运动可通过HIF-1α途径促进了低氧诱导的Bnip3介导的线粒体自噬保护机制,从而提高骨骼肌线粒体的质量。

Objective： To observe the effects of chronic hypoxia alone and hypoxia combined with exercise training on mitochondrial autophagy, and to identify the roles of hypoxia-inducible factor-1α （HIF-1α）. Method： A total 56 health male Sprague-Dawley rats were randomly divided into seven groups： normoxia control group （NC）, hypoxia control group （HC）, hypoxia combined training group （HT）, dimethyl sulfoxide（DMSO） injection and hypoxia control group （HC＋D）, inhibitor of HIF-1α YC-1 injection and hypoxia control group （HC＋Y）, DMSO injection and hypoxia training group （HT＋D）, and YC-1 injection and hypoxia training group （HT＋Y）. The hypoxia rats were subjected to hypoxia exposure in normobaric hypoxic tent. The exercise training rats were administered exercise on a motor-driven rodent treadmill in normobaric hypoxic tent. Rats in HIF-1α inhibitor YC-1 groups received peritoneal injection of the YC-1 DMSO solution at 4mg/kg body weight once a day. Rats in DMSO groups received equivolume injections of the 1% DMSO solution. All interventions were administered for continuous 4 weeks. Result： Comparing with NC group, in HC group, mitochondrial membrane potential and ATP synthesis activity showed dramatic decrease （P〈0.05）, and reactive oxygen species（ROS） generation, PINK1, Parkin, Bnip3, HIF-1α protein expression elevated significantly （P〈0.05）. Comparing with HC group in HT group, mitochondrial membrane potential, ATP synthesis activity, Parkin, Bnip3, HIF-1α protein expressions improved significantly （P〈0.05）, and ROS generation, PINK1 protein expression markedly decreased （P〈0.05）. Both in HC and HT rats, YC-1 administration significantly depressed mitochondrial membrane potential, ATP synthesis activity, Bnip3, HIF-1α protein expression （P〈0.05）, and markedly elevated ROS generation, PINK1 protein expression （P〈0.05）. Conclusion： Hypoxia combined with exercise training could significantly promote hypoxia stress induced mitochondrial autophagy, and then elevated mitochondrial quality. HIF-1α-mediated expression of BNIP3 played an important role in this induction of mitochondrial autophagy.