钟基因Per2在调节固定时间热暴露大鼠胸主动脉血管反应性变化中的作用及机制研究

Abstract Clock genes not only form the biological rhythm, but also regulate the physiological function and the pathological process. Our previous study showed that contractile effects of rats underwent fixed time heat exposure were weakened in thoracic aorta vascular ring induced by norepinephrine (NA), and the mRNA expressions of thoracic aortic clock gene Per2 and eNOS were increased. We speculated that under heat stress, fixed time heat exposure made vascular clock gene expression rhythmic changes, thus affecting contractile and relaxant function of vascular endothelial cells and smooth muscle cells. Combined with literature reports and the early stage of the preliminary results we hypothesized that Per2 may cause the function changes of the cells through influencing cell proliferation, division, beta 3 adrenergic receptors and ion state. This study is going to use the organ bath, RNA interference, flow cytometry and patch clamp technique, to observe vascular endothelial and smooth muscle cells clock gene expression level, the clock genes of factor, vascular endothelial cells and smooth muscle cell cycle regulating cell receptor expression and K ion channels in rat at different heat exposing time. This study will improve our understanding of blood vessel function of regularity response, investigate the role of clock genes in the development of heat-exposure related disease, and help us in revealing the mechanism of clock gene in regulating physiological function.

生物钟基因不仅形成生物节律，而且参与多种生理功能的调控及病理过程的发生。我们前期研究结果显示：固定时间热暴露大鼠对去甲肾上腺素（NA）诱发的胸主动脉血管环收缩效应减弱，且胸主动脉钟基因Per2及eNOS mRNA表达升高。由此推测固定时间热应激下，血管钟基因表达节律性发生改变，进而影响了血管内皮细胞及平滑肌细胞的舒缩功能。结合文献报道及前期预实验结果我们假设Per2影响了细胞增殖、分裂，改变了β3受体及细胞膜离子的功能状态而引起此反应的。本课题采用器官浴槽、干扰RNA、流式细胞及膜片钳等技术方法，观察不同时间热暴露大鼠血管内皮及平滑肌细胞钟基因表达水平，钟基因对血管内皮及平滑肌细胞细胞周期因子、细胞受体表达及K离子通道的调控作用。本研究将提高我们对血管功能规律性应答反应的认识，并进一步阐明钟基因在热应激相关疾病发生中的作用，有助于我们揭示钟基因调控机体生理功能的机制

热应激可对心血管系统造成明显损伤，高血压大鼠对湿热环境更敏感也引起了我们的关注，且其胸主动脉损伤更严重，血管舒缩反应性障碍明显加重，但其发生机制尚不明确有待于进一步探究。血管内皮细胞（VECs）在维持心血管正常生理功能中起着重要的作用。研究表明，敲除Per2基因后小鼠的血压昼夜节律消失，说明Pers基因对血压节律有调控作用，大量数据发现AngⅡ可调控Pers基因表达水平，然而在固定时间热暴露模型下，关于大鼠胸主动脉结构和功能的异常与Pers基因之间的潜在联系尚不明确。因此本课题通过建立固定时间热暴露正常大鼠与自发性高血压（SHR）大鼠模型，逐步深入探索钟基因在调节固定时间热暴露大鼠胸主动脉血管反应性变化中的作用及机制研究。同时,通过LBP干预探讨其对VECs损伤的保护作用，为后期以钟基因Per2为靶点探索其保护机制提供一定实验与理论基础。