GLUTAMATE, EXCITOTOXINS AND NEURONAL/GLIAL INTERACTIONS

描述：（改编自摘要） 主要研究者的实验室已经阐明了 几种神经变性模型的生化机制。 这些研究中的一个共同主题是代谢的作用。 抑制介导细胞死亡。 申请人建议继续 通过研究能量抑制与 代谢和激活兴奋性毒性过程，最初涉及 谷氨酸受体NMDA亚型。 研究将利用两个 模型系统：良好表征的离体鸡视网膜和大鼠视网膜 中脑培养系统 所有的实验都是一个 在以前的赠款期间完成的研究的直接结果。 代谢应激将由各种范式引起， 减少糖酵解或线粒体氧化形成的ATP 磷酸化 目的A将继续PI对急性 兴奋性毒性 这些将扩大以前的工作显示保护 通过低温对抗代谢应激和兴奋性毒性，包括 温度范围对ATP保护、测量的影响研究 和磷酸肌酸水平，以及Na+，K+-ATP酶在 这种保护。 游离脂肪酸、花生四烯酸的释放及其作用 在这种急性毒性过程中，活性氧也将 考察 目标B将仔细评估在以下情况下的作用机制： 迟发性兴奋性毒性，包括既往急性毒性是否发挥任何 作用 使用可逆的糖酵解或线粒体抑制， 时间条件将被确定，NMDA的作用也将被确定， 非NMDA受体，以及自由基和反应性 氧物种。 细胞外和细胞内 还将测定钙。 在目标C中， 各种细胞内信使系统的作用，以介导 将检查毒性。 这些将包括蛋白质的作用 激酶A和C，低温和蛋白激酶的相互作用 活化，以及大分子合成是否是必要的， 迟发性毒性。 目的D利用大鼠中脑 培养系统，以检验兴奋性毒性增强的假设 通过能量消耗，特别是在这些多巴胺能细胞中， cultures. 总的来说，这些研究将扩展以前的发现， 由该补助金资助的工作，以提供更详细的知识的作用 兴奋性毒性在神经退行性过程和相互作用 这种代谢应激的毒性导致了 CNS。

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.