GROWTH FACTORS INFLUENCE STROKE RECOVERY

最近的数据表明局灶性脑缺血导致神经死亡， 至少部分是通过启动“致命级联”， 包括兴奋性氨基酸（EAA）的释放， Ca 2+进入细胞，并导致细胞内 蛋白酶和核酸酶，以及有毒自由基和硝酸盐的产生 氧化物（NO）。 碱性成纤维细胞生长因子（bFGF）是一种神经营养因子， 一种促进体外神经元存活并保护 培养的神经元对一些侮辱和毒素，包括 缺氧、低血糖、EAA、Ca 2+离子载体、自由基和NO 初步研究，我们发现外源性bFGF减少了 成年大鼠局灶性脑缺血模型梗死体积 新生大鼠体内。 在建议的研究中，我们会进一步探讨 bFGF在局灶性脑缺血中的神经保护作用及其机制。 这些研究包括：（1）剂量、时间和途径的进一步研究 bFGF在成熟和新生儿缺血模型中的给药 大鼠，以及比较bFGF的影响，以其他表征 生长因子，（2）外源性生长因子的生物分布研究， 施用bFGF，以及bFGF受体的密度和定位 缺血后，（3）候选“神经保护” 外源性bFGF对基因表达的影响;（4）bFGF对基因表达的影响 脑血管系统 预计这些研究将提供新的 支持局灶性脑缺血后神经元存活的分子机制 缺血 P50NS108280032 该建议利用分子遗传学方法来产生和 表征缺乏神经元型一氧化氮合酶的动物模型， (NOS)基因 一氧化氮（NO）是一种由神经元产生的气体， 内皮细胞、神经胶质细胞和身体中的其他细胞。 它有 不寻常的属性，使它非常适合成为一个空间信使， 细胞间相互作用 作为一种气体，它可以自由扩散到 膜。 它与血红素结合并被血红素灭活，限制了它的一半- 秒的生命。 在神经系统中，NO与 在生理和毒性反应中建立突触可塑性 兴奋性神经递质，并可能在缺血性损伤中发挥作用 脑血管疾病 在脉管系统中，NO负责 内皮源性舒张因子（EDRF）活性，并可能是 参与静息血管张力，以及对血管张力的反应。 介质和内皮损伤，在血管系统以及 在外周血管中。 我们建议开发和表征小鼠，其中神经元NOS 基因已被选择性破坏或“敲除”，本文中称为 KN小鼠（敲除，神经元NOS）。 我们实验室正在进行的工作是 致力于小鼠的平行发展，其中血管NOS 基因敲除，KV小鼠（敲除，血管NOS）。 我们建议 在以下方面表征KN和KV小鼠的表型： 神经解剖学和脑循环。 我们希望了解 使KN和KV小鼠发育和存活的补偿机制 在缺乏内源性神经元和血管NOS基因的情况下。 这 项目还将维持KN和KV小鼠的繁殖群， 为项目1B提供足够数量的小鼠。 人们希望 这些实验将有助于我们理解 在健康和疾病中参与脑血管紧张度的机制。

Recent data indicate that focal cerebral ischemia causes neural death, at least in part, through initiation of a "lethal cascade," which includes release of excitatory amino acids (EAAs) with consequent massive Ca2+ entry into cells, and resulting activation of intracellular proteases and nucleases, and generation of toxic free radicals and nitric oxide (NO). Basic fibroblast growth factor (bFGF) is a neuronotrophic polypeptide that promotes neuronal survival in vitro, and protects cultured neurons against a number of insults and toxins, including anoxia, hypoglycemia, EAAs, Ca2+ ionophore, free radicals, and NO. In preliminary studies, we found that exogenously-administered bFGF reduced infarct volume in models of focal cerebral ischemia in mature and neonatal rats in vivo. In the proposed studies, we will further explore the phenomenon and mechanism of bFGF neuroprotection in focal ischemia. These studies include: (1) further study of the dose, timing, and route of administration of bFGF in models of ischemia in mature and neonatal rats, as well as comparison of the effects of bFGF to other characterized growth factors, (2) studies of the biodistribution of exogenously- administered bFGF, and the density and localization of bFGF receptors after ischemia, (3) studies of regulation of candidate "neuroprotective" genes by exogenous bFGF, and (4) studies of the effects of bFGF on the cerebral vasculature. It is expected that these studies will shed new light on molecular mechanisms supporting neuronal survival after focal ischemia. P50NS108280032 This proposal utilizes a molecular genetics approach to generate and characterize animal models that lack the neuronal nitric oxide synthase (NOS) gene. Nitric oxide (NO) is a gas that is made by neurons, endothelial cells, glial cells, and other cells in the body. It has unusual properties that make it well suited to be a spatial messenger in cell-cell interactions. As a gas, it is freely diffusible across membranes. It binds to and is inactivated by heme, limiting its half- life to seconds. In the nervous system, NO has been implicated in establishing synaptic plasticity, in the physiologic and toxic response to excitatory neurotransmitters, and may play a role in ischemic damage from cerebrovascular disease. In the vasculature, NO is responsible for endothelial-derived relaxing factor (EDRF) activity, and is likely to be involved in resting blood vessel tone, as well as responses to vascular mediators and endothelial injury, in the cerebrovasculature as well as in the peripheral vasculature. We propose to develop and characterize mice in which the neuronal NOS gene has been selectively disrupted or "knocked-out," herein referred to as KN mice (knock-out, neuronal NOS). Ongoing work in our laboratory is devoted to the parallel development of mice in which the vascular NOS gene is knocked-out, KV mice (knock-out, vascular NOS). We propose to characterize the phenotype of the KN and KV mice, in terms of neuroanatomy and cerebral circulation. We hope to learn about the compensatory mechanisms that allow KN and KV mice to develop and survive in the absence of the endogenous neuronal and vascular NOS genes. This project will also maintain breeding colonies of KN and KV mice, in order to provide sufficient numbers of mice for project #1B. It is hoped that these experiments will contribute to our understanding of the molecular mechanisms involved in cerebrovascular tone in health and disease.