低氧环境运动对营养性肥胖大鼠心肌细胞自噬相关蛋白表达的影响

Effects of hypoxic environmental exercise on expression of autophagy-related proteins in myocardial cells of nutritionally obese rats

目的:研究低氧环境运动对营养性肥胖大鼠心肌细胞自噬相关蛋白LC3、beclin-1、p62和AMPKα2表达的影响,为低氧环境运动改善机体形态和促进心肌组织自噬的保护功能提供实验依据。方法:7周高脂膳食诱导SD大鼠营养性肥胖模型,建模成功后随机分为常氧对照(NC)组、常氧运动(NE)组、16.3%低氧环境安静(HC1)组、16.3%低氧环境运动(HE1)组、13.3%低氧环境安静(HC2)组和13.3%低氧环境运动组(HE2),每组10只,各组均维持高脂饲料喂养。运动组大鼠进行1周适应性跑台训练,正式训练跑速为20 m/min,运动时间40 min/d,每周5 d,跑台坡度0°,持续8周。末次训练24 h后,处死大鼠并采样,采用Western blot技术检测大鼠心肌beclin-1、LC3、p62和AMPKα2的表达水平。结果:8周低氧环境耐力运动后,与NC和HC1组相比,NE、HE1和HE2组大鼠体重和Lee指数显著降低(P<0.05),心脏重量指数显著升高(P<0.05);HE1和HE2组体重显著低于NE组(P<0.05)。Western blot结果显示,NE和HE1组大鼠心肌AMPKα2蛋白表达显著低于NC组(P<0.05),而HE2组AMPKα2蛋白表达显著高于NC组(P<0.05),且显著高于其他组(P<0.05);HC2、HE1和HE2组beclin-1蛋白表达显著高于NC组(P<0.05),HE1和HE2组beclin-1蛋白表达显著高于NE组(P<0.05);其他各组LC3-II/LC3-I比值显著高于NC组(P<0.05),而p62蛋白表达显著低于NC组(P<0.05);HE1和HE2组LC3-II/LC3-I比值显著高于HC1组(P<0.05),HE2组LC3-II/LC3-I比值显著高于NE组(P<0.05)。结论:低氧环境运动可改善营养性肥胖大鼠形态,升高心脏重量指数。低氧环境或(和)运动均可上调beclin-1和LC3蛋白表达,下调p62蛋白表达,增强心肌细胞自噬水平,可能有利于提高对心肌细胞的保护功能。

AIM:To illustrate the effect of hypoxic environmental exercise on the expression of LC3,beclin-1,p62,AMPKα2 and other key factors of autophagy in cardiomyocytes of nutritionally obese rats,and to provide experi‐mental basis for hypoxic environmental exercise to improve the body shape and the protective function of myocardial tis‐sue.METHODS:The nutritionally obese SD rat model was induced by 7-week high-fat diet.After successful modeling,the rats were randomly divided into 6 groups:normoxic control(NC)group,normoxic exercise(NE)group,16.3%hy‐poxic environmental quiet(HC1)group,16.3%hypoxic environmental exercise(HE1)group,13.3%hypoxic environ‐mental quiet(HC2)group,and 13.3%hypoxic environmental exercise(HE2)group.The rats in the exercise group were pretreated with 1 week of adaptive platform training.The standard training program was conducted at the running speed of 20 m/min,the exercise time was 40 min/d,5 d/week,the platform slope was 0°,and the training lasted for 8 weeks.After the last training for 24 h,the rats were sacrificed and sampled,and the expression levels of beclin-1,LC3,p62 and AMPKα2 in rat myocardium were evaluated by Western blot analysis.RESULTS:After 8 weeks of hypoxic environmen‐tal endurance exercise,compared with NC group and HC1 group,the body weight and Lee index in NE,HE1 and HE2 groups were significantly decreased(P<0.05),and the heart weight index was significantly increased(P<0.05).The body weight in HE1 and HE2 groups was significantly lower than that in NE group(P<0.05).The protein level of AMPKα2 in NE and HE1 groups was significantly decreased(P<0.05),while that in HE2 group was significantly increased as compared with NC group(P<0.05),and that in HE2 group was significantly higher than that in other groups(P<0.05).Beclin-1 expression in HC2,HE1 and HE2 groups was significantly higher than that in NC group(P<0.05),and that in HE1 and HE2 groups was significantly higher than that in NE group(P<0.05).Compared with NC group,LC3-II/LC3-I ratio in other groups was significantly increased(P<0.05),and p62 expression was significantly decreased(P<0.05).LC3-II/LC3-I ratio in HE1 and HE2 groups was significantly higher than that in HC1 group(P<0.05),and that in HE2 group was significantly higher than that in NE group(P<0.05).CONCLUSION:Hypoxic environmental exercise im‐proves body shape and weight index of the heart in nutritionally obese rats.Hypoxia or/and exercise up-regulate beclin-1 and LC3 expression,and down-regulate p62 expression,thus enhancing autophagy of myocardial cells,which are benefi‐cial to improve the protective function for myocardial cells.Hypoxic environmental exercise has more significant effects.