GLUTAMATE, EXCITOTOXINS AND NEURONAL/GLIAL INTERACTIONS

描述：(改编自摘要) 首席调查员的实验室一直在澄清 几种神经退化模型背后的生化机制。 这些研究的一个共同主题是新陈代谢的作用 细胞死亡中的抑制作用。申请人提议继续 与研究能量抑制之间的密切相互作用 最初涉及的兴奋性毒性过程的代谢和激活 谷氨酸受体的NMDA亚型。这项研究将利用两项 模型系统：具有良好特性的体外鸡视网膜和大鼠 中脑培养系统。所有提议的实验都是 在以前的赠款期间完成的研究的直接结果。 代谢应激将由不同的范例引起，这将 减少糖酵解或线粒体氧化形成的三磷酸腺苷 磷酸化。Aim A将继续PI对急性 兴奋性毒性。这些将扩展以前显示保护的工作 抗低温引起的代谢应激和兴奋性毒性，包括 温度范围对保护、测量三磷酸腺苷影响的研究 和磷酸肌酸水平，以及Na+，K+-ATPase在 这种保护。游离脂肪酸、花生四烯酸的释放及其作用 在这种急性毒性作用下，活性氧物种也会 检查过了。目标B将仔细评估在 迟发性兴奋毒性，包括先前的急性毒性是否 角色。使用可逆性糖酵解或线粒体抑制，最佳 时间条件将被确定，NMDA和 非NMDA受体与自由基和反应性的参与 氧气物种。细胞外和细胞内的可能作用 钙也将被测定。在目标C中，关于 不同的细胞内信使系统在调节细胞周期中的作用 将进行毒性检测。这些将包括蛋白质的作用。 蛋白激酶A和C与低温的相互作用 激活，以及大分子合成是否是必要的 延迟性毒性发生。目的D将利用大鼠中脑 用于检验兴奋性毒性被增强的假设的培养系统 由于能量耗尽，尤其是在这些细胞的多巴胺能细胞中 文化。总体而言，这些研究将在之前发现的基础上进行扩展 由这笔拨款资助的工作，以更详细地了解这一角色 神经退行性变过程中的兴奋性毒性及其相互作用 这种毒性与新陈代谢应激导致能量耗竭 中枢神经系统。

DESCRIPTION: (Adapted from the abstract) The overall goal of the Principal Investigator's laboratory has been to elucidate the biochemical mechanisms underlying several models of neurodegeneration. A common theme in these studies has been the role of metabolic inhibition in mediating cell death. The applicant proposes to continue with studies on the intimate interaction between inhibition of energy metabolism and activation of excitotoxic processes initially involving the NMDA subtype of glutamate receptor. The studies will utilize two model systems: the well characterized ex vivo chick retina and the rat mesencephalic culture system. All of the proposed experiments are a direct outgrowth of studies done during previous grant periods. Metabolic stress will be induced by various paradigms which will decrease the ATP formed by glycolysis or mitochondrial oxidative phosphorylation. Aim A will continue the PI's studies on acute excitotoxicity. These will expand previous work showing protection against metabolic stress and excitotoxicity by hypothermia, and include studies of temperature range effects on protection, measurement of ATP and phosphocreatine levels, and the possible role of Na+,K+-ATPase in this protection. Free fatty acid, arachidonate release and the role of reactive oxygen species during this acute toxicity will also be examined. Aim B will carefully assess the mechanisms operative in delayed excitotoxicity including whether prior acute toxicity play any role. Using reversible glycolytic or mitochondrial inhibition, optimal temporal conditions will be determined, as will the role of NMDA and non-NMDA receptors, and the involvement of free radical and reactive oxygen species. The putative role of extracellular and intracellular calcium will also be determined. In aim C the hypotheses concerning the role of the various intracellular messenger systems to mediate the toxicity will be examined. These will include the role of protein kinases A and C, interactions of hypothermia and protein kinase activation, and whether macromolecular synthesis is necessary for the delayed toxicity to occur. Aim D will utilize the rat mesencephalic culture system to test the hypothesis that excitotoxicity is potentiated by energy depletion, especially in the dopaminergic cells of these cultures. Overall these studies will expand on previous findings from work funded by this grant to give a more detailed knowledge of the role of excitotoxicity in neurodegenerative processes and the interaction of this toxicity with metabolic stress leading to energy depletion in the CNS.