有氧运动对心肌细胞增殖/凋亡的影响及其机制探讨

目的:探讨有氧运动对大鼠心肌细胞增殖和凋亡的影响及其可能机制。方法:选取3月龄雄性SD大鼠30只,体重180～220g。随机分为正常对照组和有氧运动组,每组15只。正常对照组大鼠常规笼内生活,有氧运动组大鼠进行8wk有氧运动。运动以15m/min的速度开始,运动20min后,以3m/min的递增速度逐渐递增至20m/min,并增加跑台坡度至5°,总运动时间为60min,5d/1wk×8wk。训练结束后,测定HR、LVSP、LVEDP和±dp/dtmax等指标,判定各组大鼠心功能变化;之后开胸摘取心脏,进行组织学制片、Masson染色和心肌细胞分离与激光共聚焦显微镜观察;免疫组织化学法观察分析干细胞表面标记蛋白c-kit及其配体SCF,细胞凋亡相关因子Bax、Bcl-2和p53蛋白表达;Western Blotting法分析细胞周期与细胞增殖相关蛋白CyclinD2、CDK4和PCNA的表达。结果:与正常对照组相比,有氧运动组大鼠心系数均显著增加(P<0.05);HR和LVEDP均显著下降(P<0.05),LVSP和±dp/dtmax均显著升高(P<0.05),双核心肌细胞出现率显著增加(P<0.05),心肌组织中,c-kit和SCF的MOD值均显著升高(P<0.01),Bcl-2的MOD值显著升高(P<0.05),p53的MOD值显著下降(P<0.01),Bax的MOD值显著下降(P<0.05);心肌组织CyclinD2和CDK4蛋白表达有升高趋势,但无显著性差异,PCNA蛋白表达显著升高(P<0.01)。结论:证实了有氧运动可显著提高大鼠心功能;证实了大鼠心肌细胞存在着增殖现象;有氧运动可抑制促凋亡因子的表达,抑制心肌细胞凋亡;发现了有氧运动可促进心肌细胞增殖相关因子的表达,诱导心肌细胞的增殖。有关运动影响心肌细胞增殖与凋亡的分子机制,有待于进一步深入研究。

The Impact of Aerobic Exercise on Cardiomyocyte Proliferation / Apoptosis and Its Mechanism

Objectives:To discuss the influence of aerobic exercise on cardiomyocyte proliferation / apoptosis and its possible mechanism.Methods:Adult male Sprague-Dawley rats,weight about 180-220g,were assigned to 2 groups equally:normal control group and aerobic exercise group.Control group rats had conventional cage life and aerobic exercise group rats made 8-week aerobic exercise.Exercise was initiated at 15m/min,for 20min.The speed and duration were gradually increased to 20m/min and 60min(including the 20min at 15m/min),5° incline for per session.The exercise was performed 5 days per week for 8 weeks.After 8 weeks,to detect the cardiac function,we measured the changes in heart rate,LVSP,LVEDP,±dp/dtmax of the rats;After that,opened the thoracic and picked the heart for histologic section,Masson dyeing;Separated cardiomyocytes and observed by Laser Scanning Confocal Microscope;Stem cell factor(SCF),c-kit,Bax,Bcl-2 as well as p53 were assessed with immunohistochemistry;CyclinD2,CDK4,PCNA were assessed with Western blot analysis.Results:Compared to normal control group,heart coefficients,LVSP,LV dp/dtmax were all increased(P<0.05) in exercise group rats.HR and LVEDP were all declined(P<0.05).Moreover,aerobic exercise made dual-core cardiomyocytes increase in the rat heart(P<0.05);Furthermore,aerobic exercise made the MOD of c-kit(P<0.01),SCF(P<0.01),Bcl-2(P<0.05) increased significantly and Bax(P<0.05),p53(P<0.01) decreased significantly in the myocardium;With regard to cyclinD2 and CDK4,there were no significance(P>0.05).In addition,PCNA(P<0.01)were all increased.Conclusions:This paper confirmed the aerobic exercise could significantly improve cardiac function and the proliferation of myocardial cell;Aerobic exercise can inhibit the apoptosis of cardiomyocyte and found out that aerobic exercise could promote myocardial cell proliferation.The molecular mechanisms of exercise-induced of cardiac cell proliferation and apoptosis need further study.