心脏肥大细胞对糖尿病心房ANP分泌的调节作用及其机制

ANP, a cardiac hormone, has been known to play a crucial role in maintaining homeostasis of cardiovascular system through the hypotensive effect and inhibition of myocardial hypertrophy. Mast cells (MC) as inflammatory cells, induce histamine and rennin release by its degranulation. It has been reported that diabetes may increase the number of cardiac mast cells (CMC) and induce myocardial hypertrophy which is related to the autonomic nervous system (ANS) dysfunction. We have reported that CMC is involved in the regulation of ANP release by inhibiting atrial ANP release, in a paracrine manner, via histamine H2 receptor-cAMP signaling in physiological condition. However, the role of CMC on atrial ANP release has never been tested in pathophysiological status, diabetes in particular. . This study will be performed in diabetic rats using radioimmunoassay and molecular biology techniques. Firstly, myocardial hypertrophy index, hemodynamics and the autonomic nervous system （ANS） activity will be measured. Also, the levels of ANP/histamin/renin-related active components in plasma and cardiac tissue will be measured. Further, the related gene and protein expressions will be measured. In order to explore the roles of CMC on atrial ANP release and its mechanisms involved, modulators of CMC degranulation will be infused into the atria and then the levels of atrial ANP and cAMP in perfusate will be measured. Secondly, in order to explore whether MC stabilizer could affect the changes, cromolyn sodium, a MC stabilizer will be used and then carry out the above-mentioned studies.. We believe that the study will provide new ideas and theoretical basis for the clinical application of the CMC-ANP release connection in the prevention and treatment of diabetic cardiomyopathy.

心房钠尿肽(ANP)是一种具有降压和抗心肌肥大效应的心脏激素。肥大细胞（MC）脱颗粒能释放组胺和肾素等介质而参与炎症反应。已知糖尿病（DM）时心脏肥大细胞（CMC）数量增加，自主神经系统（ANS）功能失衡，出现心肌肥大。我们前期研究表明，生理状态下CMC释放的组胺通过H2受体-cAMP通路抑制心房ANP分泌。然而，CMC对DM心房ANP分泌的调节作用目前尚不清楚。据此，本项目以DM大鼠为研究对象，应用放免和分子生物学技术，首先检测心肌肥大指数、血流动力学和ANS活性，并观测血浆和心脏中ANP/组胺/肾素相关因子水平以及基因和蛋白表达；用MC脱颗粒相关工具药处理心房后检测灌流液中ANP和cAMP水平，其次用MC稳定剂干预DM大鼠后观测上述指标变化，探讨CMC对DM心房ANP分泌的调节作用及机制，揭示“CMC-ANP分泌”通路调控DM心肌肥大的新观点，为DM心血管并发症的防治提供新的理论依据。

心房钠尿（ANP）是一种主要由心房肌细胞合成和分泌的肽类激素。 ANP通过利尿、利钠、血管舒张和降压作用在维持心血管系统的稳态中起着至关重要的作用。肥大细胞（MC）脱颗粒能释放组胺和肾素等介质而参与炎症反应。已知糖尿病（DM）时心脏肥大细胞（CMC）数量增加，自主神经系统（ANS）功能失衡，出现心肌肥大。我们前期研究表明，生理状态下CMC释放的组胺通过H2受体-cAMP通路抑制心房ANP分泌。然而，CMC对DM心房ANP分泌的调节作用目前尚不清楚。据此，本项目以DM大鼠为研究对象，应用放免和分子生物学技术，首先检测心肌肥大指数、血流动力学和ANS活性，并观测血浆和心脏中ANP/组胺/肾素相关因子水平以及基因和蛋白表达；用MC脱颗粒相关工具药处理心房后检测灌流液中ANP和cAMP水平，其次用MC稳定剂干预DM大鼠后观测上述指标变化，探讨CMC对DM心房ANP分泌的调节作用及机制。课题组研究结果显示：1. DM病理状态下CMC脱颗粒诱导心肌肥大而参与心脏功能紊乱；2. CMC脱颗粒对DM心房ANP分泌的调节作用具有负性调控作用； 3. CMC脱颗粒后释放的组胺对DM心房ANP分泌的调节作用具有负性调控作用，其机制与H2R激活诱导的cAMP-PKA信号通路激活有关；4. DM病理状态下经典的ACE-Ang II-AT1信号通路激活而ACE2-Ang-(1-7)-Mas信号通路减弱，分别发挥抑制/促进心房ANP分泌的作用；5. 通过抑制CMC脱颗粒途径来阻断ANP分泌的降低效应能改善DM心肌肥大。本研究揭示了“CMC-ANP分泌”通路调控DM心肌肥大的新观点，为DM心血管并发症的防治提供了新的理论依据。