GLUTAMATE, EXCITOTOXINS AND NEURONAL-GLIAL INTERACTIONS

假定氨基酸的功能或代谢异常 (AA)神经递质，谷氨酸（GLU）和GABA，已被 与几种神经系统疾病的病因或后遗症有关 紊乱 GLU或GLU类似物，例如，兴奋毒素红藻氨酸盐 (KA)和使君子酸（QUIS），当直接注射到CNS时 结构会导致神经元死亡，这增加了一种有趣的可能性， 内源性兴奋性毒性活性可能参与这种 紊乱 研究表明能量的改变 GLU的代谢和正常神经元-胶质细胞代谢可能 在这种神经毒性中发挥作用。 本申请是 继续这些努力。 最近的研究表明，C1- 运输，也许通过C1-/HCO3-反向转运，可能发挥主要作用， 的基本机制中的作用 兴奋性毒性 本提案将重点关注C1- 转运抑制剂对兴奋性毒性诱导的效应 系统. 将在大鼠脑小脑中测量C1摄取 在兴奋性毒素存在下使用放射性Na 36Cl切片， 以及其它去极化剂如K+和藜芦碱。 已知 将C1转运抑制剂加入孵育物中，以观察 哪种类型的载体系统被处理激活。 小鸡胚胎的视网膜对 兴奋性毒性 发育方面的毒性将是 通过使用年龄E6至E21的视网膜进行检查，其对应于 发展的具体阶段。 结果将与 AA代谢的变化，无论是在动态方面 使用放射性前体进行测量， 通过直接测定法和免疫组织化学测定的酶。 组织切片中使用的各种C1转运抑制剂 研究将进行研究，看看哪些，如果有的话，防止 神经毒性 C1-/HCO3-系统还调节细胞内 某些细胞类型的pH值。 细胞内pH值将在 用兴奋毒素处理后的视网膜 其利用放射性苯甲酸。 还将进行研究 用新生大鼠脑和鸡胚的胶质细胞培养物 视网膜。 兴奋性毒素的直接影响，在存在和 将检查是否存在高水平的K+，包括 C1-摄取和细胞内pH变化的改变。 这些 研究应该对假设给出肯定或否定的答案 关于兴奋性毒性后遗症的潜在机制， glia的作用 更重要的是，它们可能会给新的方向， 研究神经元和神经胶质的相互作用。

Aberrations of function or metabolism of the putative amino acid (AA) neurotransmitters, glutmate (GLU) and GABA, have been implicated in the etiology or sequelae of several neurological disorders. GLU or GLU-analogs, e.g., the excitotoxins kainate (KA) and quisqualate (QUIS), when injected directly into CNS structures cause neuronal death, raising the intriguing possibility that endogenous excitotoxicity activity may be involved in such disorders. Studies have shown that an alteration in energy metabolism and normal neuronal-glial metabolism of GLU may play a role in this neurotoxicity. This application is a continuation of those efforts. Recent work has shown that C1- transport, perhaps via the C1-/HCO3- antiport, may play a major role in basic mechanisms underlying the sequelae of excitotoxicity. This proposal will focus on the use of C1- transport inhibitors on excitotoxicity-induced effects in our test systems. C1- uptake will be measured in rat brain cerebellar slices using radioactive Na36C1 in the presence of excitotoxins, and other depolarizing agents such as K+ and veratridine. Known inhibitors of C1- transport will be added to the incubations to see which type of carrier system is activated by the treatments. Chick embryonic retina is also exquisitely sensitive to excitotoxicity. Developmental aspects of toxicity will be examined by using retina of ages E6 to E21, which correspond to specific stages of development. Results will be correlated with alterations in AA metabolism, both in terms of dynamic measurements using radioactive precursors, the development of enzymes as measured by direct assay and immunohistochemistry. The various inhibitors of C1- transport used in the tissue slice studies will be studied to see which, if any, protect against neurotoxicity. The C1-/HCO3- system also regulates intracellular pH in some cell types. Intracellular pH will be measured in the retinas following treatment with excitotoxins with a method which utilizes radioactive benzoic acid. Studies will also be done with glial cultures from neonatal rat brain and embryonic chick retina. Direct effects of excitotoxins, in the presence and absence of high levels of K+ will be examined, including alterations in C1- uptake and intracellular pH changes. These studies should give positive or negative answers to hypotheses concerning mechanisms underlying excitotoxic sequelae and the role of glia. More importantly, they may give novel directions to studying the interactions of neurons and glia.