INTRACELLULAR MAGNESIUM AND EXCITOTOXICITY

镁离子是一种丰富的细胞内阳离子，对控制至关重要 广泛的细胞内突起。然而，相对较少的是 已知控制细胞内游离的动态平衡机制 镁离子，也不是关于可能干扰(镁离子)i的机制。 最近有研究表明，通常被认为具有兴奋性毒性的刺激 对神经元产生毫米级增加的培养神经元的[镁]i。 该项目的长期目标是了解[Mg2+]i在 与神经元损伤相关的过程和发展有效 基于镁离子动态平衡调控的治疗策略。这将是 通过以下具体目标来实现： 1.改变[Mg2+]i的机制的表征。[Mg2+]我会的 用镁离子敏感法测定培养的大鼠前脑神经元 荧光染料。(Mg~(2+)]_i对谷氨酸的响应特性 受体的激活将被建立，并且假设 [Mg~(2+)]i与Ca~(2+)成正比将被检测。荧光成像 将使用技术来确定细胞内镁离子的来源 放手。 2.阐明细胞内[Mg~(2+)]_i动态平衡的机制。一个人的角色 一些假定的细胞镁离子缓冲机制将被建立。 特别是，Na+/Mg2+交换有助于 将检查神经元的镁离子缓冲。 3.细胞内镁离子变化在细胞内的作用 兴奋性毒性。初步结果显示，刺激性毒性刺激 有效地提高[Mg2+]i。升高的[Mg2+]i以及 组织中镁离子丢失在兴奋性毒性中的作用将被研究。这 将确定细胞内镁离子在兴奋性毒性细胞死亡中的作用 并突出了改善神经元的新的治疗方法 受伤。 4.细胞内镁离子对细胞内钙稳态的调节。的确有 有关细胞内镁离子在细胞内的作用的信息很少。 调节神经功能。[Mg~(2+)]i变化对钙的影响 将对进入和钙离子动态平衡进行调查，并将提供另一个 [Mg2+]i变化与兴奋性毒性之间的联系。 这些研究将提供大量新的信息，关于 神经功能调节中知之甚少的阳离子。更多 重要的是，这些研究将揭示镁离子在 兴奋性毒性神经元损伤，从而突出了 会导致神经元死亡。我们还预计，这些研究将 产生关于神经元损伤治疗的新概念 对镁离子环境的操纵，从而对 治疗中风和创伤性脑损伤。

Mg2+ is an abundant intracellular cation that is critical for the control of a wide array of intracellular processes. However, relatively little is known about the homeostatic mechanisms that control intracellular free Mg2+ ([Mg2+]i, nor about mechanisms that might perturb (Mg2+]i. It has recently been shown that stimuli that are normally considered excitotoxic to neurons produce millimolar increases in [Mg2+]i in cultured neurons. The long term goal of this project is to understand the role of [Mg2+]i in processes associated with neuronal injury and to develop effective treatment strategies based on manipulation of Mg2+ homeostasis. This will be accomplished by the following specific aims: 1. characterization of mechanisms that alter [Mg2+]i. [Mg2+]i will be measured in cultured rat forebrain neurons using Mg2+-sensitive fluorescent dyes. The characteristics of the (Mg2+]i response to glutamate receptor activation will be established, and the hypothesis that the [Mg2+]i is proportional to Ca2+ will be tested. Fluorescence imaging techniques will be used to determine the source of the intracellular Mg2+ release. 2. Elucidation of the mechanisms of [Mg2+]i homeostasis. The role of a number of putative cellular Mg2+ buffering mechanisms will be established. In particular, the hypothesis that Na+/Mg2+ exchange contributes to neuronal Mg2+ buffering will be examined. 3. Determination of the role of changes in intracellular Mg2+ in excitotoxicity. Preliminary results show that excitotoxic stimuli are very effective at raising [Mg2+]i. The role of elevated [Mg2+]i as well as the effect of tissue Mg2+ loss in excitotoxicity will be investigated. This will establish the role of intracellular Mg2+ in excitotoxic cell death and highlight novel therapeutic approaches to ameliorating neuronal injury. 4. Regulation of neuronal Ca2+ homeostasis by intracellular Mg2+. There is very little information available about the role of intracellular Mg2+ in regulating neuronal function. The influence of [Mg2+]i changes on Ca2+ entry and Ca2+ homeostasis will be investigated, and will provide another link between [Mg2+]i changes and excitotoxicity. These studies will provide substantial new information about the role of a poorly understood cation in the regulation of neuronal function. More importantly, these studies will reveal the involvement of Mg2+ in excitotoxic neuronal injury and thereby highlight mechanism that contribute to neuronal death. We also anticipate that these studies will generate novel concepts about the treatment of neuronal injury based on manipulation of the Mg2+ environment and thereby positively impact the treatment of stroke and traumatic brain injury.