GLUTAMATE, EXCITOTOXINS & NEURONAL-GLIAL INTERACTIONS

该实验室的总体目标是详细研究 是几种神经退化模型的基础在本提案中，我们将 继续研究神经元-神经胶质氨基酸的相互作用 代谢，因为它涉及兴奋性毒性现象。这些研究 将主要利用鸡胚视网膜和组织培养 大鼠皮质星形胶质细胞和视网膜Muller细胞。所有这些建议 研究是在以前的资助期间所做实验的直接结果 时期作为缺血/缺氧的模型，将鸡视网膜在 无葡萄糖培养基或含葡萄糖培养基， 抑制剂（碘乙酸盐或脱氧葡萄糖，以抑制糖酵解，KCN， 抑制线粒体电子传递，二硝基酚解偶联 氧化磷酸化）。我们之前的研究表明， 抑制引起兴奋性毒性损伤，这是由抑制剂防止 NMDA受体。将深入研究这些调查结果， 了解代谢抑制和表观 激活NMDA受体。参数，如时间 ATP耗竭与急性神经毒性的关系，游离ATP的作用 自由基的产生，细胞外Mg 2+水平， 细胞内碱中毒引起的兴奋性毒性以及 还将评估细胞外pH和温度变化。的 这种影响的个体发生将被检查，并与 糖酵解和有氧代谢的发展。多胺的作用 NMDA介导的毒性也将使用各种多胺进行检查， 以及抗缺血剂艾芬地尔和SL 82.0715， 据报道与NMDA受体上的“多胺”位点相互作用。在我们 艾芬地尔保护鸡视网膜免受NMDA毒性，然而， 神经元的子集不受保护。这一点将得到进一步研究， 试图确定未受保护的神经递质表型 神经元星形胶质细胞氨基酸代谢的研究将继续进行 专注于兴奋性氨基酸和代谢的直接影响 对各种参数如糖酵解和氨基酸抑制 新陈代谢、能量充电和细胞肿胀。类似的研究将 用视网膜的主要神经胶质细胞，穆勒细胞。这些 研究应该回答一些基本的问题， 神经退行性疾病中的兴奋性毒性和神经胶质细胞的特殊作用 可能与毒性有关

The overall aim of this laboratory has been the elaboration of mechanisms underlying several models of neurodegeneration. In this proposal we shall continue our studies of the interaction of neuronal-glial amino acid metabolism as it relates to the phenomenon of excitotoxicity. These studies shall make use primarily of the embryonic chick retina and tissue culture of rat cortical astrocytes and retinal Muller cells. All of these proposed studies are the direct outcome of experiments done during previous grant periods. As a model of ischemia/hypoxia, chick retina will be incubated in glucose-free medium or glucose-containing medium with various metabolic inhibitors (iodoacetate or deoxyglucose to inhibit glycolysis, KCN to inhibit mitochondrial electron transport, dinitrophenol to uncouple oxidative phosphorylation). Our previous work has shown that metabolic inhibition causes an excitotoxic lesion which is prevented by inhibitors of the NMDA receptor. These findings will be pursued in depth in an attempt to understand the connection between metabolic inhibition and apparent activation of the NMDA receptor. Parameters such as the temporal relationship of ATP depletion and acute neurotoxicity, the role of free radical generation, extracellular Mg2+ levels, the possible potentiation of the excitotoxicity by intracellular alkalinosis and the effects of extracellular pH and temperature changes will also be assessed. The ontogeny of this effect will be examined and correlated with the development of glycolysis and aerobic metabolism. The role of polyamines in NMDA-mediated toxicity will also be examined using various polyamines as well the anti-ischemic agents ifenprodil and SL82.0715 which have been reported to interact with a "polyamine" site on the NMDA receptor. In our hands ifenprodil protects against NMDA toxicity in chick retina, however, a subset of neurons is not protected. This will be further examined and attempts made to identify the neurotransmitter phenotype of the unprotected neurons. Studies on astrocyte amino acid metabolism will be continued focusing on direct effects of exciatory amino acids and metabolic inhibition on various parameters such as glycolytic and amino acid metabolism, energy charge and cellular swelling. Similar studies will then be done with the primary glial cell of the retina, the Muller cell. These studies should answer some basic questions concerning the mechanism of excitotoxicity in neurodegenerative disorders and the special role glia might play in that toxicity.