Objective:To clarify the role of PAK1 involved in the cardioprotective effect of aerobic exercise and the precise mechanism.Methods:TAC was used to induce cardiac hypertrophy via pressure overload.Aerobic exercise was carried out in the form of swimming.C57BL6/J mice were arbitrarily divided into the following groups:a sham-operated control group (SHAM),a sham-operated control + Exercise training group (SHAM+E),a TAC group (TAC),a TAC + Exercise training group (TAC+E),and a TAC + Exercise training group + IPA-3 group (TAC+E+I).Heart weight to body weight ratio and the changes of cardiac geometry were performed to reveal the extent of cardiac hypertrophy.wheat germ agglutinin staining was performed to reveal the extent of myocyte hypertrophy;cardiac NO production,MDA levels and SOD activity were determined using ELASA kit.Western blotting was performed to investigate p-PAK1,eNOS,p-eNOS Ser114,nNOS,p-nNOS Ser1412 protein expression.Results:With time after the surgery,the HW/BW,LVM,LVPW,IVSS,the myocyte cross-sectional area and MDA were increased,the levels of SOD,p-PAK1 expression and the NO metabolite concentration were decreased in the TAC group compared with the SHAM group.Exercise training reduced HW/BW and LVM after TAC,augmented the SOD level and decreased the MDA level,and augmented p-PAK1 and NO production.IPA-3,a PAK1 inhibitor,partly abolished the effect of exercise training.More,Western blot analysis showed eNOS and nNOS protein was improved,p-nNOS Ser1412 and p-eNOS Ser114 were decreased in the TAC group compared with the SHAM group.Meanwhile,exercise training significantly increased total nNOS,p-nNOS Ser1412 and p-eNOS Ser114 expression in the TAC + E group compared with the TAC group.In addition,IPA-3 decreased the expression of both total nNOS,p-nNOS Ser1412,while the levels of eNOS and p-eNOS Ser114 was not changed in the TAC+E+I group compared with the TAC+E group.Conclusion:Aerobic exercise attenuates pressure overload-induced cardiac hypertrophy through regulating PAK1-nNOS-NO signalling in mice.%目的:有氧运动减轻压力负荷小鼠心肌肥厚中PAK1-nNOS-NO发挥的作用及机制.方法:将C57BL/6小鼠通过主动脉缩窄术(transverse aortic constriction,TAC)建立小鼠压力负荷模型,通过游泳对其进行有氧运动干预.将小鼠随机分为5组:假手术(SHAM),SHAM+有氧运动(SHAM+E),TAC,TAC+有氧运动(TAC+E)和TAC+有氧运动+IPA-3(TAC+E+I)组.通过小鼠心脏重量指数(heart weight to body weight ratio,HW/BW)变化和心脏结构变化评价心脏肥大程度,心肌组织麦胚凝集素染色评价心肌细胞肥大程度;ELASA试剂盒检测心肌组织NO水平,MDA含量和SOD活性.Western印迹检测p-PAK1,eNOS,p-eNOS Ser114,nNOS和p-nNOS Ser1412蛋白表达水平.结果:随着术后时间的延长,与SHAM组相比,TAC组HW/BW、左室质量(left ventricular mass,LVM)、左室后壁厚度(left ventricular posterior wall thickness,LvPWS)以及室间隔厚度(interventricular septal thickness,IVSS)显著增加,心肌细胞肥大,MDA含量增高,SOD活性降低,但p-PAK1蛋白含量和NO水平却显著降低.有氧运动后,TAC+E组与TAC组相比HW/BW和LVM降低,心肌细胞肥大程度减轻,组织MDA含量减少,SOD活性升高,p-PAK1表达增加,NO水平升高.而给予PAK1抑制剂IPA-3后,与TAC+E组相比,运动训练对心肌肥厚的作用减弱.TAC小鼠eNOS和nNOS表达增高,p-nNOS Ser1412和p-eNOS Ser114表达降低.运动训练可上调nNOS,p-nNOS Ser1412和p-eNOS Ser114表达;而注射IPA-3后,TAC+E+I小鼠与TAC+E小鼠相比,nNOS和p-nNOS Ser1412表达降低,eNOS和p-eNOS Ser114蛋白表达水平无明显改变.结论:PAK1-nNOS-NO信号可能是介导有氧运动减轻压力负荷小鼠心肌肥厚作用的关键信号通路.
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