【作者】 李亮；

【导师】 胡申江；

【作者基本信息】 浙江大学 ， 内科学， 2010， 博士

【摘要】 背景:法呢醇焦磷酸合成酶(FPPS)是甲羟戊酸途径中的一个重要酶,能催化合成异戊二烯中间产物,而后者在小GTP蛋白异戊二烯化过程中不可或缺。以往研究报道在年轻高血压大鼠中,FPPS的mRNA表达伴随着左室肥厚的发生和发展逐步增高。阿伦膦酸钠是临床上用于治疗骨质疏松症和转移性肿瘤的药物,被证实是临床上的药理作用主要是通过抑制FPPS的来实现的。目的:确认使用阿伦膦酸钠,能否改善自发性高血压大鼠心肌肥厚和纤维化,能否抑制心脏组织FPPS功能,并探讨其可能机制。方法:本实验取五周龄雄性大鼠24只,共分为四组。分别为正常血压对照组(WKY-C,每天生理盐水灌胃),自发性高血压大鼠组(SHR-C,每天生理盐水灌胃),自发性高血压大鼠+低剂量阿伦膦酸钠组(SLA,1 mg/kg/d)和自发性高血压大鼠+高剂量阿伦膦酸钠组(SHA,10 mg/kg/d),且每两周测一次尾动脉血压。用颈动脉插管方法测定大鼠血流动力学改变,检测全心重量、左心室重量计算来评价心脏肥厚程度,用检测羟脯氨酸含量来推断胶原含量,用Masson’s染色的方法检测胶原分布比例,用pull-down方法测定心脏组织RhoA活性,用实时定量PCR的方法检测促心脏肥厚和纤维化的指标,用Western blot的方法测定ERK1/2磷酸化水平。结果:经过12周的治疗,阿伦磷酸钠可以降低自发性高血压大鼠左室体重比(LVW/BW),羟脯氨酸含量,胶原在间质内的沉积,左室心房肽、脑钠肽,Ⅰ型和Ⅲ型胶原前体的mRNA表达。而且长期法呢醇焦磷酸合成酶抑制剂的治疗显著地降低了自发性高血压大鼠左心室RhoA的活性、ERK1/2磷酸化水平和TGF-β1的mRNA表达,而在自发性高血压大鼠对照组中以上这些改变,明显高于正常血压大鼠对照组。结论:长期法呢醇焦磷酸合成酶抑制剂的治疗可以改善心脏肥厚和纤维化的进程,其机制可能是通过抑制RhoA活性从而减少ERK1/2磷酸化和TGF-β1表达来实现。更多还原

【Abstract】 Background:Farnesyl pyrophosphate synthase (FPPS), an essential enzyme in the mevalonate pathway, catalyzes the synthesis of isoprenoid intermediates. The latter is needed for isoprenylation of small GTPase. FPPS was reported to be upregulated in young spontaneously hypertensive rats (SHR) when compared with Wistar-Kyoto (WKY) rats, and this was accompanied by development of left ventricular hypertrophy. Alendronate is used in the osteoporosis and cancer metastasis, and is confirmed to exert its pharmacological function by inhibition of FPPS.Aim:To determined whether chronic inhibition of FPPS can improve the cardiac hypertrophy and fibrosis in SHRs and explore its underlying mechanism.Methods:Eighteen male SHRs were randomly divided into three groups consisting of the distilled water group (SHR-C), the low-dose (1 mg/kg/d) alendronate group (SLA), and the high-dose (10 mg/kg/d) alendronate group (SHA). Six male age- and weight- matched WKY rats were housed as controls (WKY-C). Blood pressures were monitored by the tail-cuff method every other week. Hemodynamic was tested by carotid artery catheteration. Whole heart weight and left heart weight were obtained and calculated for evaluation of cardiac hypertrophy. Collagen content and distribution were evaluated by hydroxyproline content and Masson’s trichrome. Active RhoA was tested by the RhoA pull-down kit, and phosphorylated ERK1/2 was obtained by Western blot. The marks of pro-hypertrophy and pro-fibrosis were determined by real-time polymerase chain reaction.Results:Twelve-weeks of alendronate treatment attenuated the left ventricular weight to body weight ratio (LVW/BW), hydroxyproline content, collagen deposition in the interstitia, and gene expression of atrial natriuretic peptide, B-type natriuretic peptide, and procollagen type I/III in the SHR left ventricle, all of which were significantly higher in SHRs than in WKY rats. Furthermore, long-term treatment with an FPPS inhibitor significantly reduced RhoA activation, ERK phosphorylation, and TGF-β1 expression in the SHR left ventricle, all of which were upregulated more in SHRs than in WKY rats. In conclusion, chronic treatment with an FPPS inhibitor attenuates the development of cardiac hypertrophy and fibrosis, and the suppression of ERK1/2 phosphorylation and TGF-β1 expression with inhibition of RhoA activation may be an important mechanism.更多还原