Basic Investigations in Brain Remodeling

用选择性的磷酸二酯酶5(PDE5)抑制剂治疗中风，例如西地那非， 显著促进功能恢复，同时显著增加神经再生和 卒中发病后1天或7天开始治疗时的血管生成。在此应用程序中，我们寻求 阐明神经发生、神经母细胞迁移及其偶联的基本机制 卒中后应用西地那非治疗前后的神经再生和血管生成 神经恢复剂。我们的假设是西地那非介导卒中患者cGMP水平的升高 脑：1)通过缩短细胞周期长度促进神经前体细胞的增殖 结果是细胞周期蛋白依赖性激酶抑制物表达减少；2)增强神经母细胞 基质衍生因子-1a表达增加向缺血交界区迁移 (SDF-1a)、CXCR4和基质金属蛋白酶(MMPs)；3)促进血管生成，从而产生 促进神经发生和引导神经母细胞向缺血区迁移的允许性生态位 4)PI3K/Akt信号通路介导西地那非增强的神经发生和 神经母细胞迁移。拟议中的实验就是为了检验这些假设。我们会 研究西地那非是否能放大细胞周期动力学和调节细胞分裂的方向 脑室下区神经前体细胞和干细胞的增殖和分化。vbl.使用 逆转录病毒载体、siRNA和时间推移显微镜，我们将深入研究其分子机制，例如 SDF-1/CXCR4和MMPs促进脑缺血后神经母细胞迁移的作用 西地那非。西地那非诱导血管生成对神经发生和成神经细胞的影响 迁移，我们将测量血管生成和神经生成之间的相互作用以及分泌的蛋白质 通过内皮细胞。通过阻止SDF-1a和MMPs，我们将检查SDF-1a和MMPs 由内皮细胞分泌，介导神经母细胞迁移。使用特定的抑制剂，我们将调查 阻断PI3K/Akt信号通路是否减弱西地那非对神经发生的影响 神经母细胞迁移和血管生成。这些基础科学研究将阐明 中风后大脑自我重塑，以及cGMP如何在成人大脑中放大这一过程，这可能 导致新的方法，以促进中风康复期间的大脑重塑。

Treatment of stroke with a selective inhibitor of phosphodiesterase type 5 (PDE5), e.g.sildenafil, significantly promotes functional recovery concomitant with significant increases of neurogenesis and angiogenesis when the treatment is initiated 1 or 7 days after stroke onset. In this application, we seek to elucidate fundamental mechanisms of neurogenesis, neuroblast migration and the coupling of neurogenesis and angiogenesis after stroke with and without treatment with sildenafil as the neurorestorative agent. Our hypotheses are that sildenafil mediated increases of cGMP levels in stroke brain: 1) promote proliferation of neural progenitor cells via shortening the length of the cell cycle which results from a decreased expression of cyclin-dependent kinase inhibitors; 2) enhance neuroblast migration towards the ischemic boundary regions via increasing expression of stromal-derived factor-la (SDF-1a), CXCR4 and matrix metalloproteinases (MMPs); 3) foster angiogenesis which generates a permissive niche to promote neurogenesis and to guide neuroblast migration towards the ischemic boundary regions; and 4) the PI3K/Akt signaling pathway mediates sildenafil-enhanced neurogenesis and neuroblast migration. The proposed experiments have been designed to test these hypotheses. We will investigate whether sildenafil amplifies cell cycle kinetics and the orientation of cell division that regulate the proliferation and differentiation of neural progenitor and stem cells in the subventricular zone. Using retroviral vector, siRNA, and time-lapse microscopy, we will delve into the molecular mechanisms, e.g. SDF-1/CXCR4 and MMPs, which promote neuroblast migration in the ischemic brain after treatment with sildenafil. To examine the effects of sildenafil-induced angiogenesis on neurogenesis and neuroblast migration, we will measure the interaction between angiogenesis and neurogenesis and proteins secreted by the endothelial cells. By blocking SDF-1a and MMPs, we will examine whether SDF-1a and MMPs secreted by endothelial cells mediate neuroblast migration. Using specific inhibitors, we will investigate whether blocking the PI3K/Akt signaling pathway attenuates the effects of sildenafil on neurogenesis, neuroblast migration and angiogenesis. These basic scientific studies will elucidate the mechanisms how the brain remodels itself after stroke and how cGMP amplifies this process in the adult brain, which may lead to novel methods to facilitate brain remodeling during stroke recovery.