有氧运动对自发性高血压大鼠心肌MG53/NF-κB信号通路的影响

Effects of aerobic exercise on MG53/NF-κB signaling pathway in the myocardium of spontaneously hypertensive rats

目的:研究有氧运动对自发性高血压大鼠心脏形态与功能的影响,并探讨MG53/NF-κB信号通路在有氧运动调控高血压心脏重塑中的可能作用,为高心病的防治提供实验依据。方法:正常血压对照大鼠(Wistar-Kyoto rat,WKY)随机分为正常血压运动组(WKY-EX)和正常血压安静组(WKYSED);自发性高血压大鼠(spontaneously hypertensive rat,SHR)随机分为高血压运动组(SHR-EX)和高血压安静组(SHR-SED);每组12只;3月龄雄性。经12周跑台训练(坡度0°,20m/min,5d/w),测量尾动脉血压;Millar压力-容积系统测定心功能;WGA染色分析心肌细胞横截面积;Masson染色分析心肌胶原容积分数(CVF%);实时荧光定量PCR测定心钠肽(atrial natriuretic peptide,ANP)、脑钠肽(brain natriuretic peptide,BNP)、MG53和NF-κB p65 m RNA相对表达量;蛋白免疫印迹测定心肌MG53、NF-κB p65和p-NF-κB p65蛋白表达。结果:(1)12周有氧运动可有效降低SHR的心率和收缩压;(2)SHR-SED组CVF%和心肌细胞横截面积显著高于WKY-SED组(P<0.01),SHR-EX组CVF%显著低于SHR-SED组(P<0.01),心肌细胞横截面积无显著性差异(P>0.05);(3)与WKY-SED组相比,SHR-SED组射血分数(EF)、左心室内压上升最大速率(+dp/dtmax)和左心室内压下降最大速率(-dp/dtmax)绝对值均显著下降(P<0.01),与SHR-SED组相比,SHR-EX组EF(P<0.05)、+dp/dtmax(P<0.05)和-dp/dtmax绝对值(P<0.01)均显著增高;(4)与WKY-SED组相比,SHR-SED组心肌ANP和BNP m RNA表达量显著增加(P<0.01),NF-κB p65 m RNA表达量也显著增加(P<0.05),MG53 m RNA表达量无显著性差异(P>0.05);与SHRSED组相比,SHR-EX组心肌ANP、BNP和NF-κB p65 m RNA表达量显著降低(P<0.01),MG53 m RNA表达量显著增加(P<0.01);(5)与WKY-SED组相比,SHR-SED组心肌MG53蛋白表达水平无显著性差异(P>0.05),NF-κB p65蛋白相对磷酸化水平显著升高(P<0.01),与SHR-SED组相比,SHR-EX组心肌MG53蛋白表达水平显著升高(P<0.01),NF-κB p65蛋白相对磷酸化水平显著下降(P<0.01)。结论:有氧运动可能通过上调MG53抑制NF-κB表达,从而改善高血压心脏功能,延缓高血压性心脏病的发生发展。

Objective:To investigate the possible role of MG53/NF-κB signaling pathway in the regulation of hypertensive cardiac remodeling by aerobic exercise,and to provide a new idea for the treatment of hypertensive heart disease by combining aerobic exercise with drugs.Method:Twenty-week-old male SHR and WKY rats were randomly assigned to sedentary and exercise training groups,respectively,12 rats in each group. After 12 weeks of running platform training(incline 0°,20m/min, 5d/w), tail artery blood pressure was measured;Millar pressure-volume system was used to determine cardiac function;WGA staining was used to analyze the cell surface area of cardiomyocytes;masson staining was used to analyze myocardial collagen volume fraction(CVF%);real-time fluorescence quantitative PCR was performed to determine the relative expression of cardiac natriuretic peptide(ANP), brain natriuretic peptide(BNP),MG53 and NF-κB p65 m RNA;western blot measures the protein expression of MG53,NF-κB p65and p-NF-κB p65.Result:(1)Twenty weeks aerobic exercise effectively reduced heart rate and systolic blood pressure in the hypertensive rats.(2) CVF% and cardiac myocyte cross-sectional area were significantly higher in the SHR-SED group than in the WKY-SED group(P<0.01). CVF% was significantly lower in the SHR-EX group than in the SHR-SED group(P<0.01). There was no significant difference in cardiomyocyte cross-sectional area(P>0.05).(3)Compared with the WKY-SED group,the SHR-SED group showed significantly lower EF,+dp/dtand-dp/dtin absolute terms(P<0.01). Compared with the SHR-SED group,the SHR-EX group showed significantly higher EF(P<0.05),+dp/dt(P<0.05),and-dp/dt(P<0.01) in absolute terms.(4)Compared with the WKYSED group,myocardial ANP and BNP m RNA expressions were significantly increased in the SHR-SED group(P<0.01),and NF-κB p65 m RNA expression was also significantly increased(P<0.05),while MG53 mRNA expression had no significant difference(P>0.05). Compared with those in the SHR-SED group, myocardial ANP, BNP and NF-κB p65 m RNA expression was significantly lower(P<0.01) and MG53 mRNA expression was significantly higher(P<0.01) in the SHR-EX group.(5) Compared with the WKY-SED group, myocardial MG53 protein expression level had no change in the SHR-SED group(P>0.05) and NF-κB p65 protein phosphorylation level was significantly increased in the SHR-EX group(P<0.01) and compared with SHR-SED group, myocardial MG53 protein expression level was significantly increased in the SHR-EX group(P<0.01)and NF-κB p65 protein phosphorylation level was significantly decreased(P<0.01).Conclusion:Aerobic exercise may inhibit NF-κB expression through up regulation of MG53,thereby improving hypertensive cardiac function and delaying the development of hypertensive heart disease.