METABOLISM OF GLUTAMATE IN RETINA

视网膜中谷氨酸的代谢

• 批准号: 2701395
• 负责人: BARRY S. WINKLER
• 金额: $ 22.42万
• 依托单位: OAKLAND UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 1994
• 资助国家: 美国
• 起止时间: 1994-05-01 至 1999-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2701395
• 关键词: Muller's cell; aminoacid metabolism; bioenergetics; brain metabolism; carbon dioxide; gamma aminobutyrate; glutamates; glutamine; laboratory rat; neurotransmitter metabolism; retina

The broad, long-term goal of this proposal is to understand the central role of glutamate and its related metabolites in retinal function. We will investigate the importance of glutamate, glutamine and gamma-aminobutyric acid and their relationship to carbohydrate metabolism and how these interrelationships are expressed in retinal neurons and Muller glial cells. Our working hypothesis is that glutamate provides an important source of carbons for energy production under aerobic conditions in the retina and that its metabolism is different in various retinal cells or layers. The major objective of this five year proposal is to identify the substrate sources and cellular sites of metabolic CO2 production in the rat retina Specific Aims proposed to accomplish the objectives are: 1. To test the hypothesis that CO2 production from exogenous glutamate requires glutamine synthesis and export by the Muller cells, its subsequent entry and conversion to glutamate in neuronal cells and further metabolism by: a) measuring the production of CO2 in whole retina from exogenous glutamine and glutamate in the presence or absence of glutamine synthetase inhibitors; and b) measuring glutamate metabolism and enzyme activities in monolayer cultures of rat and human Muller cells. 2. To determine the effects of activation of glutamate receptors by exogenous glutamate on energy production from glucose and on the metabolic pathways studied in Aim 1. Isolation of receptor- and substrate-dependent effects of glutamate will be achieved with the use of uptake blockers and receptor agonists and antagonists. 3. To determine the relative importance of glutamate transaminase, dehydrogenase, and decarboxylase because of the known heterogeneity in expression of these enzymes in the retina by: a) measuring their effects on CO2 formation from radiolabeled glutamate in the presence of specific enzyme inhibitors; and b) measuring the regional metabolism of glutamate and enzyme distribution in partial retinas, enriched in either outer or inner retinal layers. The measurements will include glycolysis, oxygen uptake, formation of carbon dioxide from isotopically labeled substrates, light-induced electrical activity, high energy phosphate levels, enzyme activities, leakage of lactic acid dehydrogenase, and morphological analyses. Our approach will provide new insights into the relationships between glutamate and retinal energy metabolism and the linkage between glutamate as an energy source and glutamate as an excitatory transmitter.

该提议的广泛长期目标是了解中心 谷氨酸及其相关代谢产物在视网膜功能中的作用。我们将 研究谷氨酸，谷氨酰胺和γ-氨基植物的重要性 酸及其与碳水化合物代谢的关系以及它们如何 相互关系在视网膜神经元和Muller Glial中表达 细胞。 我们的工作假设是，谷氨酸提供了重要的 在有氧条件下的能源生产的碳来源 视网膜，其代谢在各种视网膜细胞或 层。这五年提案的主要目标是确定 代谢CO2产生的底物来源和细胞位点 大鼠视网膜 提出实现目标的具体目标是：1。测试 假设来自外源谷氨酸的二氧化碳生产需要谷氨酰胺 穆勒细胞的合成和导出，其随后进入和 转化为神经元细胞中的谷氨酸，并进一步代谢：a） 测量外源谷氨酰胺中整个视网膜中二氧化碳的产生 在存在或不存在谷氨酰胺合成酶的情况下 抑制剂； b）测量谷氨酸代谢和酶活性 大鼠和人穆勒细胞的单层培养物。 2。确定 外源谷氨酸激活谷氨酸受体的影响 葡萄糖和在研究中研究的代谢途径上产生能源 目标1。谷氨酸的受体和底物依赖性作用的分离 使用摄取阻滞剂和受体激动剂以及 对手。 3。确定谷氨酸的相对重要性 由于已知 这些酶在视网膜中表达的异质性通过：a） 测量其对放射性标记谷氨酸谷氨酸二氧化碳形成的影响 特定酶抑制剂的存在； b）测量区域 部分视网膜中谷氨酸和酶分布的代谢， 富含外部或内部视网膜层。测量结果 包括糖酵解，摄入氧气，形成二氧化碳 同位素标记的底物，光诱导的电活动，高 能量磷酸盐水平，酶活性，乳酸泄漏 脱氢酶和形态分析。我们的方法将提供新的 洞悉谷氨酸和视网膜能量之间的关系 代谢和谷氨酸作为能源和 谷氨酸作为兴奋性发射器。