【作者】 齐洪涛；

【导师】 刘志华；

【作者基本信息】 苏州大学 ， 内科心血管， 2007， 博士

【摘要】 研究目的:观察辛伐他汀对慢性心力衰竭兔心室重构、心功能的影响,探讨其作用机制。研究方法:24只新西兰白兔分为4组,第1组为假手术组,2、3、4组联合应用主动脉瓣破坏术及腹主动脉缩窄术建立慢性心力衰竭模型;第2组为心力衰竭对照组;第3组为早干预组,术后即给予辛伐他汀5mg·kg-1·d-1灌胃,连续6周;第4组为晚干预组,术后4周开始给予辛伐他汀5mg·kg-1·d-1灌胃,连续4周。观察开始及结束时进行超声心动图检查,测量左心室舒张末期内径(LVIDd)、左心室收缩末期内径(LVIDs)、室间隔厚度(IVSd)、左心室后壁厚度(LVPwd)、左心室射血分数(EF)、左心室长轴缩短率(FS)。心导管法记录左心室舒张末压(LVEDP),测量结束后处死动物、取标本。测量心脏重量、左心室重量、心脏/体重、左心室/体重;光镜检查心肌组织切片,TUNEL法检测心肌细胞凋亡指数。RT-PCR检测过氧化物酶体增殖物激活受体(γPPARγ)mRNA水平; Western blotting法测定细胞膜RhoA、细胞浆细胞周期蛋白B1(cyclin B1)、细胞核PPARγ、细胞核核因子-κB(NF-κB)、细胞浆糖原合成激酶3β(GSK3β)、细胞核β-连环蛋白(β-catenin)等蛋白表达水平;用[γ-32P]GTP测定Rho GTPase,免疫沉淀法检测GSK3β活性;电泳迁移率变动分析(EMSA)法测定NF-κB活性。结果:辛伐他汀早干预组和晚干预组左心室室间隔厚度(IVSd)、左心室收缩期内径(LVIDs)、、左室最大舒张末期压(LVEDP)显著低于心力衰竭对照组,左心室射血分数(EF)、左心室长轴缩短率(FS)显著高于心力衰竭对照组(P<0.05-0.01),心脏重量、左心室重量、心脏/体重、心肌细胞凋亡指数(AI)显著低于心力衰竭对照组(P<0.05-0.01)。另外,辛伐他汀早干预组左心室后壁厚度(LVPWd)、左心室舒张期内径(LVIDd)、左心室/体重显著低于心力衰竭对照组(P<0.05-0.01)。与心力衰竭对照组相比,辛伐他汀早干预组和晚干预组细胞膜RhoA蛋白表达减少(P<0.01)、Rho GTPase活性减弱(P<0.01)、细胞浆cyclinB1蛋白表达减少(P<0.01);细胞核PPARγ基因及蛋白表达增加(P<0.01),细胞核NF-κB活性及蛋白表达降低(P<0.01)、细胞浆GSK3β活性增加(P<0.01)、细胞核β-catenin表达减少(P<0.01)。结论:在心脏前后负荷增加或心力衰竭发生后,给予辛伐他汀类药,可有效抑制心室肥厚、心肌细胞凋亡,改善心室重构,增强心功能;其机制包括:(1)他汀类药物抑制RhoA蛋白转位于细胞膜,从而抑制Rho GTPase活性,抑制细胞浆cyclinB1蛋白表达,抑制心肌细胞增殖;(2)他汀类药物增加PPARγ基因及蛋白表达,抑制心肌细胞核NFκB亚基p65蛋白表达及活性;(3)增加细胞浆GSK3β活性,抑制心肌细胞核β-catenin表达。更多还原

【Abstract】 Objection: This study was to evaluate the effects of simvastatin on ventricular remodeling and heart function and investigate the mechanisms of cardioprotective effects of simvastatin.Methords: 24 rabbits were divided 4 groups, group I: received sham operation as health control. In other groups, aortic regurgitation and coarctation of ascending aorta were operated in rabbits. Group II was received no drugs. In group III, rabbits were given simvastatin 5mg·kg-1·d-1 after the operation. In group IV, rabbits were given simvastatin 5mg·kg-1·d-1 after 4 weeks of operation. At begin and end of treatment period, Echocardiographic evaluations were performed and left ventricular end diastolic pressure was measured with catheter. At the end of experiment, heart weight, left ventricular weight, body weight, heart weight/body weight radio, left ventricular weight/body weight radio were measured.Myocardial apoptosis identified by in situ dUTP nick-end labeling method and apoptotic index (AI) was calculated.Western blotting analysed RhoA expression in cardiomyocyte membrane and cyclin B1 expression in cardiomyocytes cytosol. Rho GTPases activity was determined by [γ-32P] GTP- binding assays. RT-PCR was used to evaluate peroxisome proliferator-activated receptor (PPAR)γmRNA expression. Western blotting analysed PPARγexpression in cardiomyocytes nuclear.Electropharesis mobility shift assay (EMSA) System was used to evaluate NF-κB activity.Western blotting analysed NF-κB expression in cardiomyocytes nuclear. Glycogen Synthase Kinase (GSK)3βactivity was determined by immunoprecipitation.Western blotting analysed GSK3βexpression in cardiomyocytes cytosol andβ-catenin expression in cardiomyocytes unclear. Results: Compared with CHF rabbits, in rabbits received early and late treatment of simvastatin, the heart weight, left ventricular weight, heart weight/body weight radio were significantly less (p<0.05-0.01, respectively), The IVSd, LVIDs were significantly decreased (p<0.05-0.01, respectively), the EF and FS were significantly higher (p<0.05- 0.01, respectively), The apoptotic index (AP) was significantly less (p<0.01), The LVEDP were significantly lower (p<0.05), cardiomyocyte size decreased. In early treatment group, left ventricular weight/body weight radio, LVIDd and LVPWd were significantly less than CHF rabbits also (p<0.05-0.01, respectively).In rabbits treated by simvastatin, the expression of RhoA in cardiomyocytes membrane and cyclin B1 in cardiomyocytes cytosol were significantly decreased (p<0.01, respectively). Simvastatin significantly diminished the activity of Rho GTPase (p<0.01, respectively).Simvastatin significantly promoted the PPARγmRNA and protein expression (p<0.01, respectively). The expression and activity of NF-κB were sinificantly inhibited in rabbits treated by simvastatin (p<0.01, respectively).Simvastatin significantly promoted the activity of GSK3βin cardiomyocytes cytosol and significantly reduced the expression ofβ-catenin in cardiomyocytes unclear (p<0.01, respectively).Conclusion: Given simvastatin in chronic heart failure rabbit models could prevent heart enlarge and inhibit the development of cardiac hypertrophy and prevent the cardiomyocytes apoptosis, improve cardiac function. The mechanisms include: (1) Simvastatin inhibite the expression of RhoA in cardiomyocytes membrane and Rho GTPase activity in cardiomyocytes cytosol.Simvastatin decreae expression of cyclinB1 in cardiomyocytes cytosol. (2) Simvastatin promote PPARγmRNA and protein expression in cardiomyocytes nuclear, inhibite NF-κB expression and activity in cardiomyocytes nuclear. (3)Simvastatin promote GSK3βactivity in cardimyocytes cytosol and reduce the expression ofβ-catenin in cardiomyocytes nuclear.更多还原