GLIAL REACTION TO ISCHEMIC BRAIN INJURY

缺血性脑损伤是死亡和残疾的主要原因， 有效的治疗。扩散性抑郁（SD）可加重脑损伤 如果它发生在缺血前不到一天。 SD也可以 如果损伤发生在缺血前1-3天，即所谓的缺血性损伤， 宽容 因此，神经细胞和组织具有内源性能力， 来调节自身的损伤程度 SD本身是无害的。 此外，它在与SD相同的时间段内诱导星形胶质细胞增生。 诱导缺血耐受。 由于神经胶质激活神经元，SD诱导 神经胶质增生可能是SD发展所需的关键转化， 诱导对缺血性损伤的耐受性。因此，总的目标是 该建议是定义基本的信令机制， 负责SD，因此开始定义所需的基本触发器， SD诱导的神经胶质增生和SD诱导的对兴奋性毒性损伤的耐受性。 实验将系统地结合联合收割机， 准备与现代调查工具，探索基本的 SID的生理和解剖变化。 海马器官培养 （HOTC）将在整个项目中使用，因为：（A）HOTC是 一个完整的脑组织区域， 体内发现的关系，但HOTC在体外存活数月;（B） HOTC的微环境条件可以容易地控制;（C） HOTC内的单个细胞可以在空间和时间上被跟踪;（D） 我们已经证明HOTC支持SD并发展成这样的星形胶质细胞增生， 在vivo中看到因此，SD、SD诱导的神经胶质增生和SD诱导的耐受 需要几天的时间来进化，现在可以第一次在 体外 这意味着，实验的优势，容易获得和 体外制剂的微环境控制可应用于 在细胞和分子水平上回答“机械”问题， 需要完整组织的事件。 膜片钳技术，计算机- 基于成像策略和分子生物学技术， 实现以下具体目标。(1)检查 缝隙连接功能变化的时空动态 神经元和星形胶质细胞之间与SD。(2)检查 SD诱导电流的时空变化和同一性 海马锥体细胞(3)研究细胞和 SD间质Ca ~（2+）变化。(4)研究如何调节Ca 2+或 SD的酸碱变化影响SD诱导的神经胶质增生和对 兴奋性毒性损伤

Ischemic brain injury is a major cause of death and disability with few effective treatments. Spreading depression (SD) can enhance brain injury if it occurs less than a day before ischemia. However, SD also can reduce injury if it occurs 1-3 days before ischemia, so-called ischemic tolerance. Thus, neural cells and tissues have an endogenous ability to modulate the extent of their own injury. SD itself is noninjurious. Furthermore it induces astrogliosis over the same time period as SD- induced ischemic tolerance. Since glia vitalize neurons, SD-induced gliosis may be a key transformation needed for the development of SD- induced tolerance to ischemic injury. Accordingly, the general goal of this proposal is to define the fundamental signaling mechanisms responsible for SD and so begin to define the basic triggers needed for SD-induced gliosis and SD-induced tolerance to excitotoxic injury. Experiments will systematically combine an innovative in vitro preparation with modern investigative tools to explore fundamental physiologic and anatomic changes of SID. Hippocampal organ cultures (HOTCs) will be used throughout this project because: (A) the HOTC is an intact area of brain tissue that maintains many cell-to-cell relationships found in vivo yet HOTCs survive in vitro for months; (B) microenvironmental conditions of HOTCs can be easily controlled; (C) individual cells within the HOTC can be followed in space and time; (D) we have shown that HOTCs support SD and develop astrogliosis like that seen in vivo. Thus, SD, SD-induced gliosis and SD-induced tolerance which require days to evolve, can now be examined for the first time in vitro. This means that the experimental advantages of easy access and microenvironmental control of in vitro preparations can be applied to answer 'mechanistic' questions at the cellular and molecular level of events that require intact tissues. Patch clamp technology, computer- based imaging strategies, and molecular biologic techniques will be used to accomplish the following specific aims. (1) Examine the spatiotemporal dynamics of gap junction functional changes between neurons and between astrocytes associated with SD. (2) Examine the spatiotemporal changes and identity of SD-induced currents in hippocampal pyramidal cells. (3) Examine the mechanisms of cellular and interstitial Ca2+ changes of SD. (4) Examine how modulation of Ca2+ or acid-base changes of SD influence SD-induced gliosis and tolerance to excitotoxic injury.