METABOLIC AND HOMEOSTATIC MECHANISMS IN RETINA AND RPE

视网膜和 RPE 的代谢和稳态机制

• 批准号: 6605693
• 负责人: BARRY S. WINKLER
• 金额: $ 32.6万
• 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 2005-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6605693
• 关键词: Krebs' cycle; Muller's cell; aspartate transaminase; bioenergetics; carbon dioxide; electrophysiology; gamma aminobutyrate; glutamates; glutamine; guinea pigs; homeostasis; ion transport; laboratory rat; mitochondria; phosphorylation; retina; retina detachment; retinal pigment epithelium; visual photoreceptor

DESCRIPTION (Adapted from the applicant's abstract): There are two long-range goals in this renewal application. The first goal is to understand the mechanism by which various classes of cells in mammalian retina obtain energy. The classical view is that glucose is the primary substrate for retinal energy metabolism and that photoreceptor cells have the highest metabolic rates. A different and more recent view (termed "metabolic trafficking") is that Muller cells are the principal, if not sole, producers of lactate, which then serves as the primary fuel for the mitochondria in photoreceptor cells and retinal neurons. A third preferred substrate, glutamate, initially metabolized by the enzyme aspartate aminotransferase (AAT), has also been proposed. The following specific aims will evaluate these contrasting hypotheses of retinal metabolism. The cellular sites of glucose uptake and phosphorylation will be identified in studies with labeled 2-deoxyglucose. Mitochondrial production of carbon dioxide will be measured with labeled glucose, glutamate, or lactate with and without inhibitors of AAT in order to establish the metabolic priority of substrates utilized by rat and guinea pig retinal mitochondria and the role of AAT in regulating the rate of the Krebs cycle activity. In addition, the specific contribution of Muller cells to glycolysis and respiration in whole retinas will be evaluated by using gliotoxins to selectively kill these cells in rat and guinea pig retinas: cell morphology and activity of glutamine synthetase will be used as markers of toxicity. These experiments will provide new and important information regarding the three competing hypotheses for retinal energy metabolism and provide a basis for a better understanding of the vulnerability of specific retinal ischemia. The second goal expands on these studies of retinal metabolism to understand roles played by ion transport and metabolic trafficking across the RPE in photoreceptor function and retinal adhesion. The proposed experiments were developed following the striking observation that incubation of rat eyecups in bicarbonate-free medium quickly leads to retinal detachment. Experiments will also examine retinal re-attachment by restoration of bicarbonate to the bathing medium or the addition of certain drugs (e.g., diamox) which have been reported to decrease retinal edema. A long-term goal of the second project is to understand better the nature of the interactions between the retina and RPE and factors regulating retinal detachment.

描述（改编自申请人的摘要）：有两个远程 此续订申请中的目标。第一个目标是了解 哺乳动物视网膜中各类细胞获取能量的机制。 经典观点认为葡萄糖是视网膜能量的主要底物 新陈代谢，并且感光细胞具有最高的代谢率。一个 不同且更新的观点（称为“代谢贩运”）是 Muller 细胞是乳酸的主要（如果不是唯一的话）生产者，然后提供乳酸 作为感光细胞和视网膜中线粒体的主要燃料 神经元。第三种优选的底物是谷氨酸，最初由 还提出了天冬氨酸氨基转移酶（AAT）。下列 具体目标将评估这些视网膜代谢的对比假设。 葡萄糖摄取和磷酸化的细胞位点将在 使用标记的 2-脱氧葡萄糖进行的研究。线粒体产生二氧化碳 将用标记的葡萄糖、谷氨酸或乳酸进行测量，有或没有 AAT 抑制剂以确定底物的代谢优先级 大鼠和豚鼠视网膜线粒体的利用以及 AAT 在 调节克雷布斯循环活动的速率。另外，具体 Muller 细胞对整个视网膜糖酵解和呼吸的贡献 将通过使用胶质毒素选择性杀死大鼠中的这些细胞来进行评估 和豚鼠视网膜：细胞形态和谷氨酰胺合成酶活性 将用作毒性标记。这些实验将提供新的和 关于视网膜的三个相互竞争的假设的重要信息 为更好地理解能量代谢提供基础 特定视网膜缺血的脆弱性。第二个目标扩展了这些 研究视网膜代谢，以了解离子转运和 光感受器功能和视网膜中 RPE 的代谢运输 附着力。所提出的实验是在令人震惊的事件之后开发的 观察大鼠眼杯在不含碳酸氢盐的培养基中快速孵育 导致视网膜脱离。实验还将检查视网膜 通过将碳酸氢盐恢复到沐浴介质或沐浴介质中来重新附着 添加某些药物（例如 Diamox），据报告可以减少 视网膜水肿。第二个项目的长期目标是更好地理解 视网膜和 RPE 之间相互作用的性质和因素 调节视网膜脱离。