PGC-1a调控的线粒体ROS通路在糖尿病心脏对缺血损伤易感性中的作用及淫羊藿苷的保护机制研究

PGC-1α plays an important regulatory role in mitochondria ROS pathway in heart. Our previous study showed that, during the early period of ischemia injury, ROS increases and PGC-1α experssion decrease, suggesting that PGC-1a regulatory mitochondria ROS pathway is involved in the vulnerability of diabetic hearts to ischemia injury. The icariin has a cardioprotective effect, but the molecular mechanism of action is unclear. In this study, on the basis of the previous work, we applied the recombinant DNA and RNA interference techniques with the rats of diabetic ischemic myocardium and the in vitro cultured neonatal SD rat cardiomyocytes as the experimental model to observe: ① PGC-1α regulatory mitochondrial ROS pathway expression changes in the early myocardial tissue of rats of diabetic myocardial ischemia and the intervention effect of icariin; ② The influence of high sugar hypoxia culture on the PGC-1α regulatory mitochondrial ROS pathway in the myocardial cells and the intervention effect of icariin; ③ observe the influence of up regulation/down regulation of PGC-1a singal on the mitochondrial ROS pathway of cardiocytes in the high -sugar hypoxic environment by constructing the carriers of PGC-1a overexpression and expression inhibition (RNAi silencing of PGC-1a gene); in vivo observe the influence of injection exogenous PGC-1a gene transfection of myocardial tissue on the diabetic ischemic heart structure and function.

PGC-1α在心脏线粒体ROS代谢中发挥重要调节作用。我们已有研究表明，糖尿病心脏在缺血损伤早期ROS产生增加，PGC-1α表达减低，推测PGC-1a调控的线粒体ROS通路参与了糖尿病心脏对缺血损伤的易感性。淫羊藿苷具有心脏保护作用，但其分子作用机制不清楚。本研究在已有工作基础上，以糖尿病心肌缺血大鼠和体外培养的新生SD大鼠心肌细胞为实验模型，应用基因重组和RNA干扰技术，观察：①糖尿病心肌缺血大鼠早期心肌组织内PGC-1a调控的线粒体ROS通路的表达变化及淫羊藿苷的干预效应；②高糖缺氧培养对心肌细胞内PGC-1a调控的线粒体ROS通路的影响及淫羊藿苷的干预效应；③通过构建PGC-1a过度表达和表达抑制（RNAi沉默PGC-1a基因）的载体，观察上调/下调PGC-1a信号对高糖缺氧环境心肌细胞线粒体ROS通路的影响；在体观察注射外源PGC-1a基因转染心肌组织对糖尿病缺血心脏结构和功能影响

本课题严格按照预定研究计划进行。本研究通过建立糖尿病心肌缺血大鼠模型和离体实验观察到了，糖尿病心肌缺血早期PGC-1a表达下调，ROS活性增加，抗氧化酶SOD2、NADPH等下调，心功能下降，通过基因转染技术上调心脏PGC-1a表达，可以降低氧化应激，改善心功能，提示PGC-1a调控的线粒体ROS通路参与了糖尿病心肌缺血的早期发生，为临床治疗糖尿病心肌缺血提供了新策略。应用淫羊藿苷干预模型大鼠，观察到淫羊藿苷通过上调心肌细胞PGC-1a，降低氧化应激，改善心功能，初步阐明淫羊藿苷对糖尿病心肌缺血的保护作用和相关的分子信号机制。另外，我们发现PGC-1a过表达通过增加血管内皮细胞NO产生和内皮松弛降低了盐敏感高血压小鼠血压，提示上调PGC-1a对于预防和治疗高血压是一有效策略。最后，我们还进一步研究发现，PGC-1a通过减低NOX1调节的ROS产生抑制了血管紧张素II诱导的大鼠平滑肌细胞增殖，提供了保护血管防止动脉粥样硬化发生的一有效策略。