运动锻炼上调M3R对MI大鼠心脏产生保护效应及其机制探讨
Cardioprotective Effect and Its Mechanism of Exercise Training Up-Regulating the Expression of M3 Receptor on Myocardial Infarction in Rats
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摘要: 目的:探讨运动上调M3受体(M3R)对心肌梗死(MI)大鼠心脏产生保护效应及其机制。方法:雄性SD大鼠48只,随机分为正常对照组(C),心梗组(MI),心梗+中强度持续有氧运动组(ME1),心梗+高强度间歇运动组(ME2),每组12只。C组常规饲养,MI组采用左冠脉前降支结扎法(LAD)建立MI模型。ME1和ME2组心梗手术1周后进行跑台运动,60min/次,1次/d,5d/1周×8周。ME1组以10m/min×5min,再以3m/min速度递增至16m/min。ME2组以10m/min×10 min后,逐渐递增至25 m/min×7 min;之后以15 m/min×3min间歇运动,依次交替进行。训练结束后次日,腹腔麻醉进行颈动脉插管测定LVSP、LVEDP、±dp/dtmax等指标,评定心功能变化。之后迅速开胸摘取心脏,分别进行组织学制片、Masson染色观察心肌胶原纤维变化,免疫荧光法观察分析心肌M3R表达,Western Blot法检测心肌M3R、MEK1/2、p-ERK1/2、ERK1/2、Bcl-2和Bax蛋白表达。结果:MI组胶原容积百分比(CVF%)和LVEDP较C组显著升高(P<0.01),LVSP和±dp/dtmax较C组均显著降低(P<0.01)。MI后可见心肌M3R阳性染色,且M3R、MEK1/2、p-ERK1/2/ERK1/2表达较C组均显著升高(P<0.01),Bcl-2/Bax比值较C组显著降低(P<0.01)。ME1和ME2组CVF%和LVEDP较MI组均显著降低(P<0.01),ME1组-dP/dt max较MI组显著升高(P<0.01),ME2组LVSP较MI组显著升高(P<0.01)。ME1和ME2组均可见心肌M3R阳性染色,M3R、MEK1/2、p-ERK1/2/ERK1/2表达较MI组显著增加(P<0.01),Bcl-2/Bax比值较MI组显著升高(P<0.01,P<0.05),ME1组和ME2组间无显著差异。结论:持续有氧运动和高强度间歇运动均可上调心梗心肌M3R-MEK1/2-ERK1/2通路,抑制心肌细胞凋亡,改善心肌纤维化程度,保护心梗大鼠心功能。心梗心肌M3R-MEK1/2-ERK1/2-细胞凋亡途径与持续和间歇运动方式及运动强度关系不密切。Abstract: objective:Cardioprotective effect and mechanism of exercise training up-regulating the expression of M3 receptor on myocardial infarction.Methods:48 male Sprague-Dawley rats were randomly assigned to four groups(n=12,per group):control group(C),myocardial infarction group(MI),moderate-intensity aerobic exercise with myocardial infarction group(ME1)and high-intensity aerobic interval exercise with myocardial infarction group(ME2),Rats in C group are breed normally.MI was induced by ligation of the left anterior descending(LAD)coronary artery in MI group。Rats in ME1 and ME2group take treadmill exercise for8 wk after 1wk post-operation.ME1 group running began at the speed of 10m/min for 5min,then accelerate from 3m/min to 16m/min.ME2 group running began at the speed of 10m/min for 10 min,then the speed increases to 25 m/min,after 7min,slow down at the speed of15m/min for 3min.Take the process alternatively.The total exercise time of ME1 and ME2are both 60 min,5d/1wk×8wk.LVSP,LVEDP,±dp/dtmax and the cardiac function changes are measured after training.Myocardial collagen fibers were observed by histological section and Masson staining.The expression of myocardial M3 R was observed and analyzed by immunoflourecence.The myocardial protein content of M3 R,MEK1/2,P-ERK1/2,ERK1/2 and apopto-sis related Bcl-2and Bax were assayed by Western Blot.Results:MI increased CVF and LVEDP(P<0.01),but decreased LVSP and-dp/dtmax(P<0.01).After MI myocardial M3 positive staining,after MI M3 protein expression significantly higher(P<0.01),MEK1/2,PERK1/2/ERK1/2 protein expression were significantly increased(P<0.01,P<0.01),after the MI the Bcl-2/Bax expression significantly reduced(P <0.01).ME1 and ME2 group CVF%,LVEDP significantly reduced(P<0.01),ME1-dp/dtmaxsignificantly increased(P<0.01),ME2 LVSP increased significantly(P<0.01).ME1 and ME2groups were identified myocardial M3,ME1 and ME2 M3 protein expression significantly increased(P<0.01,P<0.01).ME1 and ME2group Bcl-2/Bax expression significantly reduced in the MI group(P<0.01,P<0.01).ME1 and ME2index had no significant difference.Conclusions:Moderate-intensity aerobic exercise and high-intensity aerobic interval exercise can upregulate the M3R-MEK1/2-ERK1/2signaling pathway,thus inhibit the apoptosis of myocardial cells,reduce myocardial interstitial fibrosis and promote cardiac function after MI.
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