【作者】 何莉梅；

【导师】 李元建；

【作者基本信息】 中南大学 ， 药理学， 2011， 硕士

【摘要】 研究背景高血压是危害人类健康的常见疾病,能引起心、肾、脑、视网膜等多组织器官损伤。心血管重构是高血压疾病常见的适应性反应。心肌重构包括心肌细胞肥大、心肌纤维化以及心肌细胞凋亡,是引起心功能失代偿进而导致慢性心力衰竭的重要因素；血管重构是血管为适应内外环境变化而发生的结构和功能改变,涉及细胞增殖、肥大、凋亡、细胞迁移、细胞外基质产生等一系列血管壁细胞生物学变化,是高血压疾病恶化的重要病理基础。缬沙坦为强效血管紧张素Ⅱ1型受体拮抗药(angiotensionⅡtype 1 receptor blocker, ARB),目前已成为治疗高血压的一线药。然而,缬沙坦口服生物利用度低(25%),且个体差异较大。因此,对其进行结构改造,提高其在肠道的吸收率具有重要意义。根据前体药物设计,已成功将缬沙坦结构改造成为一系列化合物,经药代动力学筛选发现在这些化合物中缬沙坦甘氨酸乙酯(Valsartan Ethyl Ester, VSTGEt)具有生物活性,且其吸收率比缬沙坦要高约6倍。本实验将比较VSTGEt与缬沙坦的降压与抑制心血管重构的作用。已知缬沙坦降压作用机制是通过阻断血管紧张素er61型受体(AT1)而发挥作用。文献报道,血管紧张素Ⅱ(AngⅡ)能激动突触前膜血管紧张素Ⅱ受体,抑制降钙素基因相关肽(calcitonin gene-related peptide, CGRP)释放。CGRP是辣椒素敏感的感觉神经递质,具有强效舒血管效应与抑制血管重构作用。因此,本实验将在比较缬沙坦与缬沙坦甘氨酸乙酯降血压和抑制心血管重构的基础上,并探讨其作用是否与调节CGRP有关。研究方法50只雄性自发性高血压大鼠(spontaneously hypertensive rats,SHR),16周龄,适应性饲养2周后随机分成6组。(1)SHR模型组(n=6)；(2)溶媒组(n=6)；(3)缬沙坦低剂量组(10 mg/kg/day,n=9)；(4)缬沙坦高剂量组(30mg/kg/day, n=9)组；(5)缬沙坦甘氨酸乙酯低剂量组(10mg/kg/day, n=10); (6)缬沙坦甘氨酸乙酯高剂量组(30mg/kg/day, n=10)。正常雄性Wistar大鼠(16周龄,n=8)作为正常血压对照。动物每周称重,以调整给药量。大鼠血压用无创尾动脉血压仪检测。26周时超声心动图分析心室壁厚度。实验结束时,动物麻醉后取心肌、胸主动脉、背根神经节、以及肠系膜上动脉。HE染色法和Masson染色检测大鼠心肌和血管重构和纤维化；Real time PCR检测大鼠心肌组织中CollagenⅠ、CollagenⅢmRNA以及背根神经节中CGRP mRNA表达；免疫组织化学方法检测大鼠肠系膜上动脉CGRP表达；放射免疫法检测血浆CGRP浓度。结果动物经药物治疗8周后,能显著降低SHR的血压与抑制心血管重构：(1)缬沙坦与缬沙坦甘氨酸乙酯显著降低血压,且呈剂量依赖趋势,但两种药物相比并无显著性差异；(2)缬沙坦与缬沙坦甘氨酸乙酯显著改善左室后壁厚度和室间隔厚度,并呈剂量依赖趋势,缬沙坦与缬沙坦甘氨酸乙酯对心室壁厚度作用两组间无显著性差异；(3)缬沙坦与缬沙坦甘氨酸乙酯两个剂量均显著性减少左心室重量,并呈剂量依赖趋势,但缬沙坦与缬沙坦甘氨酸乙酯对心室重量的影响两种药物相比没有显著性差异；(4)缬沙坦与缬沙坦甘氨酸乙酯显著抑制心肌细胞肥大,减轻心肌炎症反应,抑制胸主动脉和肠系膜上动脉肥厚,且呈剂量依赖趋势,但缬沙坦与缬沙坦甘氨酸乙酯的作用相比,并无显著性差异；(5)缬沙坦与缬沙坦甘氨酸乙酯显著减轻心肌间质和肠系膜上动脉纤维化,其作用呈剂量依赖趋势,但缬沙坦与缬沙坦甘氨酸乙酯的作用无显著性差异；(6)缬沙坦与缬沙坦甘氨酸乙酯显著上调血浆CGRP浓度,上调背根神经节CGRP mRNA表达以及肠系膜上动脉CGRP表达,呈剂量依赖趋势,但缬沙坦与缬沙坦甘氨酸乙酯的作用无显著性差异。结论缬沙坦与缬沙坦甘氨酸乙酯均能降血压并能够显著改善心血管重构,两者降压和抑制心血管重构作用相当,其机制可能与促进CGRP合成与释放有关。更多还原

【Abstract】 BACKGROUNDHypertension is a common disease that impacts human health. It may cause tissue injury such as heart, kidney, brain and artery. Cardiovascular remodeling is the most important adaptation response. Cardiac remodeling includes cardiomyocyte hypertrophy, apoptosis and myocardial fibrosis, which may cause cardiac functional decompensation and ultimately results in heart failure. Vascular remodeling is structure and function alteration responsible for environment change, and is always related to a series of biological changes such as proliferation, hypertrophy, apoptosis, migration and production of extracellular matrix of vascular cells, and acts as an important pathology that aggravates hypertension. Valsartan, an angiotensionⅡtype 1 receptor blocker (ARB), is one of the first-line antihypertensive drugs. It inhibits cardiovascular remodeling besides decreasing blood pressure. However, valsartan has very poor bioavailability (25%) and the individual variation is large.Thus, it is very important to elevate the absorbance in intestinal. We use valsartan as substrate and synthesised a seris of compounds, and selected VSTGEt for it is more active than others. The absorbance of VSTGEt in intestinal is 6 times higher than VST. In this study, we will compare the Effects of VST and VSTGEt on blood pressure and cardiovascular remodeling.It is well known that valsartan blocks angiotensionⅡtype1 receptor and decreases blood pressure. It has been well established that angiotension II stimulates angiotensionⅡtype 1 receptor on presynaptic membrane, and inhibits the release of calcitonin gene-related peptide (CGRP). CGRP, the neurotransmitter of capsaicin sensitive sensory nerves, possesses complex cardiovascular actions such potent vasodilator effect and inhibiting vascular remodeling. In the present study, we therefore compared the effects of valsartan and VSTGEt on blood pressure and cardiovascular remodeling, and explored the effects of valsartan and VSTGEt on the synthesis and release of CGRP.METHODSFifty sixteen-week male spontaneously hypertensive rats (SHR) were divided randomly into 6 groups:SHR group (n=6); solvent group (0.5% CMC-Na,2 ml/day, n=6); SHR and valsartan groups (10 or 30 mg/kg/day, n=9); SHR and VSTGEt groups (10 or 30 mg/kg/day, n=10). Sex-and age-matched normotensive Wistar rats (n=8) were treated with water by gavages as normal control. And rats were weighed weekly for adjusting drug dose. Blood pressure was measured per week by noninvasive blood pressure monitoring. Rats had a cardiac ultrasonography at 26-week-old, and then were sacrificed to isolate hearts, thoracic aorta, mesenteric artery and dorsal root ganglion. HE and Masson staining were used to see hypertrophy and fibrosis in heart and artery. The mRNA expression of Collagen I and collagen III in heart and CGRP in dorsal root ganglion were measured by real-time PCR. The expression of CGRP in superior mesenteric artery was examined by immunohistochemistry. CGRP concentration in plasma was determined by radioimmunoassay.RESULTSAfter administered drug for eight weeks, SHR showed a significant decrease in blood pressure and cardiovascular remodeling:(1) VST and VSTGEt significantly lowered blood pressure in a dose-dependent tendency, but the two drugs had no significant difference. (2) VST and VSTGEt significantly decreased IVS and LWPT in a dose-dependent tendency, but there was no significant difference between the two drugs. (3) VST and VSTGEt significantly reduced left ventricular weight in a dose-dependent tendency, but the results didn’t show significant difference between the two drugs. (4) VST and VSTGEt significantly inhibited cadiomyocyte hypertrophy, decreased cardiac inflammation reaction and inhibited hypertrophy in thoracic aorta and superior mesenteric artery in a dose-dependent tendency, but the effects of the two drug had also no significant difference. (5) VST and VSTGEt alleviated cardiac interstitial fibrosis and vascular fibrosis in a dose-dependent tendency and there was no significance between the two drugs. (6) VST and VSTGEt notably increased plasma CGRP concentration, CGRP mRNA expression in dorsal root ganglion and CGRP protein in superior mesenteric artery in a dose-dependent tendency, but no significant difference was seen between the two drugs.CONCLUSIONVST and VSTGEt can decrease blood pressure and improve cardiovascular remodeling markedly, which may be related to stimulation of synthesis and release of CGRP.更多还原