运动预适应上调Nrf2改善急性低压低氧大鼠脑海马线粒体氧化应激机制探讨

Upregulation of Nrf2 by exercise preconditioning improves mitochondrial oxidative stress in rat hippocampus after acute hypobaric hypoxia

【目的】观察运动预适应对急性低压低氧大鼠脑海马线粒体氧化应激的影响,并探讨人红细胞衍生核因子2样蛋白2(nuclear factor-erythroid derived 2-related factor 2,Nrf2)在其间的生物学效应。【方法】大鼠分为对照组(normal control group,NC)、急性低氧组(acute hypoxia group,AH)和运动预适应+急性低氧组(exercise preconditioning+acute hypoxia group,EP+AH)。EP+AH组大鼠在常氧环境下进行6周跑台训练,坡度5°,速度17 m/min,60 min/d,5次/周。AH组和EP+AH组大鼠置于低压低氧舱8 h,压力0.06 MPa,氧含量10%±2%。比色法检测线粒体锰型超氧化物歧化酶(manganese superoxide dismutase,MnSOD)活性和丙二醛(malondialdehyde,MDA)含量,二氯荧光素法检测线粒体活性氧(reactive oxygen species,ROS)产生速率,ELISA法检测白介素-1β(interleukin-1β,IL-1β)含量,Western blotting检测Nrf2、硫氧还蛋白2(thiredoxin2,Trx2)、同源性磷酸酶张力蛋白诱导激酶1(phosphatase and tensin homologue-induced putative kinase 1,PINK1)和苄氯素1(Beclin1)蛋白表达。【结果】AH组与NC组比较,脑海马IL-1β含量、Beclin1蛋白表达、线粒体ROS产生速率和MDA含量显著升高(P<0.05~0.01),Nrf2和Trx2蛋白表达、MnSOD活性显著降低(P<0.05~0.01)。EP+AH组与AH组比较,脑海马IL-1β含量、线粒体ROS产生速率和MDA含量显著降低(P<0.05~0.01),Nrf2、Trx2、PINK1、Beclin1蛋白表达及MnSOD活性显著升高(P<0.05~0.01)。【结论】运动预适应可通过上调Nrf2及其下游抗氧化酶和线粒体自噬,抑制急性低氧导致的脑海马氧化应激和炎症反应。

【Objective】To investigate the effect of exercise preconditioning on mitochondrial oxidative stress in rat hippocampus after acute hypobaric hypoxia,and to probe into the biological effect of nuclear factor-erythroid derived 2-related factor 2(Nrf2).【Methods】Rats were randomly divided into three groups:normal control group(NC),acute hypoxia group(AH),and exercise preconditioning+acute hypoxia group(EP+AH).Rats in EP+AH group underwent six-week treadmill training in the plain at a speed of 17 m/min,-5°grade for 60 min/day.Rats in AH and EP+AH groups were placed in hypobaric hypoxia chamber at 0.06 MPa pressure and 10%±2%oxygen for consecutive 8 hours.The malondialdehyde(MDA)content and manganese superoxide dismutase(MnSOD)activity were determined by colorimetric method.Mitochondrial reactive oxygen species(ROS)generation rates were measured by dichlorofluorescein.The interleukin-1β(IL-1β)content was detected by ELISA,and the expression levels of Nrf2,thiredoxin2(Trx2),phosphatase and tensin homologue-induced putative kinase 1(PINK1)and Beclin-1 were detected by Western blotting.【Results】Compared with the NC group,the content of IL-1β,Beclin1 protein expression,mitochondrial ROS production rate and MDA content in the AH group significantly increased(P<0.05~0.01),and the protein expression of Nrf2 and Trx2 and MnSOD activity significantly reduced(P<0.05~0.01).Compared with the AH group,the content of IL-1β,mitochondrial ROS production rate and MDA content in EP+AH group significantly reduced(P<0.05~0.01),and Nrf2,Trx2,PINK1 and Beclin1 protein expression and the activity of MnSOD were significantly increased(P<0.05~0.01).【Conclusion】Exercise preconditioning could promote Nrf2 and its downstream antioxidant enzyme as well as mitophagy,which in turn inhibited the oxidative stress and inflammation in hippocampus induced by acute hypobaric hypoxia.