硫化氢对高血压大鼠交感神经紧张性调控的中枢炎症机制和神经修复机制研究

Hypertension remains a major public health problem. Sympathetic excessive activation is involved in the pathogenesis and development of hypertension and damage of target organ. Inhibiting the excessive activation of the sympathetic has become an important strategy in prevention and treatment of hypertension. Inflammation is involved in many cardiovascular diseases. Hydrogen sulfide (H2S) can reduce blood pressure. What relation between the sympathetic nerve activity and inflammation? This project is designed to detect the level of H2S and inflammatory factor in serum of hypertensive patients and then record blood pressure, heart rate and renal sympathetic nerve activity in conscious spontaneous hypertensive rats by intraperitoneal administration of H2S, to observe the effect of H2S on sympathetic outflow. The mRNA and protein expression of inflammatory factors in the rostral ventrolateral medulla (RVLM) will be assessed by western blot and real time PCR. The DNA methylation pattern of inflammatory factors gene promoter were assayed to reveal the epigenetic mechanism of H2S in RVLM. The inhibitor of TNF-α or AAV-siRNA for p44/42MAPK will be microinjected into RVLM to elucidate the mechanism of H2S at gene level. Proliferation and differentiation of neural stem cells will be detected by immunofluorescence, to elaborate the neural repair mechanism of H2S which inhibits expression of inflammatory factor then enhances the repair of neural stem cells in order to reduce the sympathetic activation. It is hopeful to provide a novel strategy to treat hypertension by reducing the sympathetic activation.

交感神经过度激活参与高血压的发生发展，抑制交感过度激活是防治高血压的重要手段。炎性反应参与多种心血管病变。H2S可降低血压，是否通过调控中枢炎症？本项目通过高血压病人血浆H2S与炎症因子水平，自发性高血压大鼠给予H2S时清醒的血压、心率及肾交感神经放电，血浆和脑脊液中炎症因子水平，明确H2S作用下交感激活与炎症因子的关系。应用westernblot和RT-PCR检测炎症因子蛋白和mRNA水平，DNA检测启动子甲基化水平，从分子和表观遗传学揭示炎症机制；采用腺病毒携带siRNA敲低RVLM炎症因子生成酶和RVLM给予TNF-α抑制剂，明确H2S降低中枢炎症的基因靶点。应用免疫组化、细胞培养等检测神经干细胞增殖分化，阐述H2S激活神经干细胞修复而降低交感激活。总之，从表观遗传学机制对炎症的抑制和从神经干细胞修复改善中枢功能两方面揭示H2S降低高血压交感过度激活的中枢机制，为高血压治疗提供靶点。

高血压是最常见的心血管疾病之一，其致残致死率高，给社会和家庭带来了沉重负担。交感神经过度激活是其重要的发病因素之一，抑制交感过度激活是防治高血压的重要手段。炎性反应参与多种心血管系统疾病，而中枢炎症是否与交感过度激活有关尚不清楚。硫化氢作为内源性的气体信号分子，其含量降低与高血压发病有关。那么H2S是否通过降低中枢炎症改善交感紧张性而发挥降压作用非常值得研究。本项目首先研究发现高血压患者血压升高，血浆中炎症因子水平明显增加，而H2S水平明显降低。在WKY和SHR大鼠发现，SHR大鼠血压升高，以肾神经放电为代表的交感传出活动明显增强，血浆中炎症因子水平明显增加， H2S水平明显降低。长期中枢给予H2S可改善上述表现，因此明确血浆H2S水平明显降低可能高血压时炎症反应增加，交感紧张性活动增强有关。随后发现SHR大鼠下丘脑交感中枢RVLM区炎症因子水平明显增加，其交感神经过度激活。而通过给予正常对照WKY大鼠侧脑室微量注射LPS诱导中枢炎症，可引起其交感紧张性的增强，血压升高，证实交感中枢的炎症反应导致了高血压的发病。进一步研究发现LPS通过激活WKY大鼠RVLM区小胶质细胞的NLRP3炎性小体导致中枢炎症。在SHR大鼠RVLM区也存在中枢小胶质细胞NLRP3炎性小体的激活，而应用炎性小体的抑制剂MCC950可以抑制NLRP3炎性小体激活，从而降低SHR大鼠交感中枢的交感紧张性进而降低动物血压。在侧脑室显微注射H2S供体可明显抑制RVLM区小胶质细胞NLRP3炎性小体激活，降低交感中枢的紧张性，从而降低血压。本研究揭示了高血压发病的中枢炎症机制，同时明确了H2S改善血压的中枢作用靶点，为高血压的防治提供新的实验依据，具有重要的理论意义和应用价值。