从功能成像- Rho GTPases信号研究补阳还五汤迭加丰富环境刺激对神经干细胞定向迁移的调控

It is a very important but difficult question in the field of stroke rehabilitation how to promote the proliferation of endogenous neural stem cells and modulate its targeted migration.Domestic and foreign research confirmed that enriched environment including multiple interference factors of environment could promote neurogenesis and enriched environment was an effective and low risk rehabilitation means.Invigorating yang for recuperation decoction combined with enriched environmental stimulus could promote endogenous neural stem cells migrating to ischemic region which was the important result of previous project National Natural Science Foundation of China. Based on previous research, the brain functional region of invigorating yang for recuperation decoction and enriched environment stimulus as well as the combination will be confirmed by positron emission tomography (PET) which is a kind of cerebral metabolic imaging technology.The targeted migration and distribution of endogenous neural stem cells will be traced by MRI in order to observe the modulation pattern of invigorating yang for recuperation decoction combined with enriched environmental stimulus on targeted migration of newborn neurons. Moreover the key process of invigorating yang for recuperation decoction combined with enriched environmental stimulus on targeted migration of newborn neurons will be explained by the Rho GTP enzyme which is the molecular switch of cell migration. The characteristic of our research is to explore the mechansim of invigorating yang for recuperation decoction combined with enriched environmental stimulus from the integral level -the change of brain function and the molecular level -signal molecules of cell response .Our objective is to provide theoretical evidences forcefully for application of the Chinese herb combined with enriched environmental stimulus environment correctly and timely.

探索促进内源性神经干细胞增殖、定向迁移的新方法是卒中康复研究的热点和难点。国内外研究证实存在多个干预因子的环境（丰富环境）能促进神经发生，是有效、低风险、低成本的康复手段。补阳还五汤迭加丰富环境刺激可促进内源性神经干细胞向缺血损伤区迁移是前一项国家自然基金项目研究中获得的重要结果。在此基础上，本项目拟采用PET脑代谢成像技术确定补阳还五汤、丰富环境刺激及二者联合作用的脑功能区，通过MRI技术示踪内源性神经干细胞迁移，从功能影像水平动态观察补阳还五汤迭加丰富环境刺激对神经干细胞定向迁移的调控模式。并进一步从细胞迁移的"分子开关"Rho GTP酶信号通路揭示其调控内源性神经干细胞定向迁移的关键环节。将整体水平的脑功能变化与细胞应答反应的信号分子相结合，研究补阳还五汤迭加丰富环境刺激对神经干细胞定向迁移的调控机制，为中药治疗和丰富环境刺激在卒中康复中有机结合运用提供强有力的理论支持。

缺血性脑卒中发生后，神经细胞大量死亡，神经网络的复杂联系受到严重损害，由此引发各种神经功能缺失症状。本项目提出益气活血中药联合丰富环境促进内源性神经功能重建的构想，设计了补阳还五汤迭加丰富环境刺激康复模式。采用线栓法致中动脉栓塞大鼠模型，将micro MRI的解剖成像、功能成像与micro PET/CT分子成像结合，建立基于多模态影像技术和方法的药理评价体系， 18F-FDG micro PET/CT对脑葡萄糖代谢进行功能显影； DTI成像技术示踪灰白质微结构损伤及修复；3DTOF-MRA结合pCASL-PWI技术监测血流动力学改变及侧枝循环的重建。通过不同模态信息的融合，对脑缺血大鼠灰白质结构及神经血管功能进行可视化和定量化。为补阳还五汤迭加丰富环境刺激促进脑缺血大鼠组织结构和神经血管功能重塑提供客观的影像学证据。在此基础上，监测神经-血管-轴突髓鞘病理学改变，以“分子开关”Rho GTP酶信号介导的轴突导向信号为重点，揭示补阳还五汤迭加丰富环境刺激促进神经发生、血管新生、轴突再生的关键调控环节。研究结果显示补阳还五汤迭加丰富环境刺激对神经功能的整体康复作用较单独补阳还五汤治疗或丰富环境刺激更有优势。补阳还五汤迭加丰富环境刺激可减轻脑缺血大鼠脑组织萎缩，促进灰、白质结构重塑；并通过改善缺血脑区血流灌注及侧枝循环，上调促血管生长信号，促进神经发生、血管新生，同时在促进神经-血管功能重塑的过程中，通过上调Rho GTPases正向调控子Rac、 Cdc42表达，抑制负向调控子RhoA的异常活化，对吸引性导向因子（Netrin-1/DCC）和排斥性导向因子（Slit-2/Robo-1）表达产生了重要的调控作用。该研究工作将推进环境干预措施在脑功能康复中的临床应用，为中药治疗和丰富环境刺激在卒中康复中有机结合运用提供强有力的理论支持。