SHH信号通路激活对急性心肌梗死大鼠缺血心肌血管再生的作用

目的 探讨SHH(sonic hedgehog)信号通路激活对急性心肌梗死(AMI)大鼠缺血心肌血管再生作用及机制。方法 雄性成年SD大鼠80只，体质量（150~200）g采用结扎大鼠左前降支的方法制备AMI大鼠模型，随机分为单纯心肌梗死(AMI)组，外源性重组人SHH蛋白（rhSHH）处理组，SHH信号通路抑制剂Cyclopamine(CYC)处理组，连续处理7 d后，利用VIII因子免疫组织化学染色测定rhSHH对AMI大鼠缺血心肌微血管密度的影响；TTC染色观察各组心肌梗死面积；ELISA和RT-PCR方法测定AMI大鼠缺血心肌促血管再生相关的指标血管内皮生长因子(VEGF),碱性成纤维细胞生长因子(bFGF)及血管生成素(Ang)-1的血清和mRNA表达；Western blot检测各组SHH信号通路相关蛋白SHH,SMO,Gli-1的蛋白表达。结果 与AMI组相比，rhSHH处理后缺血心肌微血管密度显著增加（P<0.05），心肌梗死面积减小（P<0.01），血管生长因子VEGF，bFGF，Ang-1的血清水平和mRNA表达显著增加（P<0.01），心肌梗死边缘区SHH信号通路下游靶分子(SHH，SMO，Gli-1)的蛋白表达显著增加（P<0.05）；这种影响可以被SHH信号通路抑制剂Cyclopamine所逆转（P<0.01）。结论 激活SHH通路可增加缺血心肌血管生长因子VEGF，bFGF，Ang-1的表达，促进急性心肌梗死大鼠的血管再生。

Activation of SHH signaling pathway promotes vasculogenesis in rats with acute myocardial infarction

AIM To investigate the role of activation of the SHH signaling pathway in promoting vasculogenesis in rats with acute myocardial infarction and investigations of these mechanisms. METHODS Sixty male Sprague-Dawley rats weighing approximately (150-200) g were subjected to left anterior descending coronary artery ligation. The rats were randomly divided into three groups: acute myocardial infarction (AMI) operation group, exogenous recombinant human SHH protein group (rhSHH treatment group) and a cyclopamine treatment group. Collateral microvessel density was measured by VIII factor immunohistochemical analysis, and VEGF, bFGF and Ang-1 expressions in ischemic myocardium of acute myocardial infarction rats were observed using ELISA and RT-PCR. Effects of SHH expression on pathway signal protein expression were analyzed using Western blot method. RESULTS Compared with those in AMI group, treatment with rhSHH following AMI increased microvessel density (P<0.05), reduced myocardial infarction area (P<0.01), enhanced coronary collaterals by stimulating plasma level and mRNA expressions of VEGF, bFGF and Ang-1 in ischemic myocardium (P<0.01), and increased the relative density of protein levels of SHH, SMO and Gli-1 (P<0.05). However, these effects were significantly suppressed by the application of the inhibitor of cyclopamine (P<0.01). CONCLUSION Activation of SHH signaling pathway in rats with acute myocardial infarction increases the expressions of VEGF, bFGF and Ang-1, which promotes angiogenesis in rats with acute myocardial infarction.