RhoA/Rho激酶通路在模拟失重所致动脉结构和功能重建中的作用

The definite mechanism underlying structural and functional remodeling of artery system induced by microgravity still remains unclear. Thus, there's still no pertinent countermeasure for the moment. Results from recent studies have indicated that multiple pathways could be involved in the process of artery remodeling induced by microgravity/simulated microgravity, in which the RhoA/Rho kinase pathway may play a central role as the intersection of all these pathways probably involved. To test this hypothesis, we take the tail-suspended rat as the animal model of simulated microgravity and then carry out the following procedures: ①test the level of RhoA and Rho kinase expression of the artery system in rats induced by short-, medium- and long-termed simulated microgravity, and determine the correlation between the changes and time course of simulated microgravity; ②detect the expression and phosphorylation of the key molecules in RhoA/Rho kinase pathway, and ascertain the mechanisms underlying their alterations; ③observe the relationship between RhoA/Rho kinase pathway and the arterial vasoreactivity, proliferation and apoptosis of VSMCs, L-Ras system, ROS, NOS and inflammatory responses, and determine the impact of this pathway on the structure and function of the artery system; ④detect if the specific inhibitor of Rho kinase could prevent the alterations of the pathways mentioned above, and finally confirm if RhoA/Rho kinase pathway plays the pivotal role as the intersection in the structural and functional remodeling of artery system. Our study supplies significant importance for explaining the mechanisms involved in the arterial remodeling induced by microgravity, and proposes a new idea for the medical guarantee in the activity of manned space flight.

模拟失重所致动脉结构和功能重建的机理尚未完全阐明，故尚无满意防护措施。近年研究提示：多条通路参与失重/模拟失重下动脉结构和功能重塑，而RhoA/Rho激酶通路可能作为众多通路的交汇点，在动脉重建中发挥关键作用。本研究拟以大鼠尾部悬吊模拟失重影响，进行以下工作：①观测短、中、长期悬吊大鼠动脉RhoA、Rho激酶表达水平，确定其改变与模拟失重时程是否相关；②检测RhoA/Rho激酶通路关键分子的表达及磷酸化水平，确定其活性改变的途径；③观察RhoA/Rho激酶通路与动脉反应性、VSMCs增殖与凋亡、L-Ras系统、ROS通路、NOS通路及炎症反应的关系，确定其对动脉结构与功能的影响；④观测Rho激酶抑制剂是否能影响上述各通路的改变，探讨RhoA/Rho激酶通路是否动脉结构和功能重塑的关键作用分子。本工作对阐明航天失重下动脉重建的机理具有理论意义，亦可能为载人航天医务保障新思路提供实验依据。

模拟失重所致动脉结构和功能重建的机理尚未完全阐明，对其影响亦难以完全防护。近年研究提示：多条通路参与失重/模拟失重下动脉结构和功能重塑，而RhoA/Rho激酶通路可能作为众多通路的交汇点，在动脉重建中发挥关键作用。为检验这一假说，本工作采用国际通用的尾部悬吊方法模拟失重的主要影响，运用多种方法技术，从多方面综合检测了模拟失重下不同部位动脉血管RhoA/Rho激酶（ROCK）通路活性及相关蛋白表达的变化，研究了上述变化与NO-NOS通路、炎性反应通路及血管平滑肌细胞（vascular smooth muscle cells, VSMCs）反应性等多条通路之间的关系，并深入分析了RhoA/ROCK通路的改变在模拟失重所致动脉重建中的作用。本工作主要结果如下：1.模拟失重可致大鼠动脉组织中ROCK的表达和活性发生区域特异性改变，具体表现为，在颈总动脉，ROCK的表达和活性均显著降低，在胸主动脉，ROCK的表达不变但活性显著增强，而在腹主动脉，ROCK的表达显著增强但活性显著降低；2. 模拟失重显著降低大鼠股动脉中ROCK的表达及其对下游靶通路的作用，包括与动脉收缩反应性直接相关的MLCP/MLC通路，以及间接相关的NF-κB/iNOS/NO通路，二者可能共同导致股动脉收缩功能降低；3. RhoA/ROCK通路蛋白表达和活性在模拟失重大鼠脑动脉和肠系膜小动脉中分别发生下调和上调的变化，提示其在模拟失重所致阻力动脉功能改变中可能发挥代偿性保护作用；4. 在模拟失重大鼠脑动脉和肠系膜小动脉中，RhoA可与BKCa通道的不同亚基之间发生共定位结合，且抑制/激活RhoA可显著上调/下调BKCa通道功能，提示RhoA/BKCa通道可能组成功能复合体，共同代偿模拟失重所致阻力动脉收缩功能重建。5. RhoA/ROCK通路活性变化可能参与了模拟失重大鼠肾内小动脉收缩功能的改变。肾内动脉功能实验、蛋白表达与定位实验提示HU大鼠肾内动脉 ROCK蛋白表达显著降低而活性显著增强。本工作对阐明航天失重下动脉重建的机理具有理论意义，亦可能为载人航天医务保障新思路提供实验数据。