ANTIOXDANT SYSTEMS AND AGE-RELATED MACULAR DEGENERATION

老年性黄斑变性(AMD)是导致失明的主要原因 在60岁以上的美国人口中。可获得的证据表明 黄斑变性是由于视网膜色素功能恶化所致。 上皮(RPE)。视网膜色素上皮在光感受器中的关键作用 碎片消化，RPE的富光富氧位置 这为氧化损伤提供了环境，并积累了 随着年龄的增长，RPE中荧光色素的含量可能受到 氧化过程结合起来表明氧化损伤是一种潜在的 AMD的病因。 抗氧化剂系统保护RPE免受细胞损伤 由氧化过程引起的。谷胱甘肽(GSH)是一种天然的 存在的三肽，通过与之反应起抗氧化剂的作用 限制非酶氧化过程的自由基和过氧化物质。 通过这种解毒作用，谷胱甘肽起着重要的保护作用。 在许多细胞系统中，化学物质或其他来源造成的氧化损伤， 包括肝、肺、肾。初步研究表明 外源性GSH对培养的人RPE细胞的保护作用 氧化损伤。这项提案的目的是描述 RPE运输和合成GSH的能力，以确定如何 这些功能会随着年龄的增长而变化，从而更好地理解GSH的作用 在RPE中防御氧化损伤。 RPE细胞转运谷胱甘肽的能力将通过摄取He来衡量 放射性标记的GSH。谷胱甘肽转运的进一步特征将是 钠依赖、pH依赖、浓度依赖的研究 和运输系统的专一性。RPE合成谷胱甘肽将是 高效液相色谱法测定细胞内GSH耗竭后的含量 用顺丁烯二酸二乙酯(DEM)孵育细胞 GSH的放射性标记氨基酸前体。谷胱甘肽转运速率 可以测量合成，并与捐赠者的年龄进行比较。 进一步深入了解GSH在黄斑变性中的作用将是 台盼蓝拒染法测定细胞活力。 然后在培养的细胞中添加谷胱甘肽或氨基酸 用于确定哪种前体更好地保护RPE免受氧化 受伤。 通过了解谷胱甘肽在保护视网膜色素中的作用 上皮细胞氧化损伤，这些研究将提供真知灼见 探讨AMD的发病机制，并可能提出治疗方向 对这种毁灭性的疾病负责。

Age-related macular degeneration (AMD) is the leading cause of blindness in the over 60 year old American population. Available evidence suggests that AMD results from a deterioration in function of the retinal pigment epithelium (RPE). the critical role played by the RPE in photoreceptor debris digestion, the light-rich and oxygen-rich location of the RPE which provides an environment for oxidative damage, and the accumulation of fluorescent pigments in the RPE with aging probably stimulated by oxidative processes combine to suggest oxidative damage as a potential cause of AMD. Antioxidant systems protect the RPE from the cellular damage that can be induced by oxidative processes. Glutathione (GSH) is a naturally occurring tripeptide which functions as an antioxidant by reacting with free radicals and peroxides to limit nonenzymatic oxidative processes. Through this detoxification, GSH plays a major role in protection against oxidative injury from chemicals or other sources in many cell systems, including the liver, lung, and kidney. Preliminary studies have demonstrated that exogenous GSH can protect cultured human RPE cells from oxidative injury. The aims of this proposal are to characterize the ability of the RPE to transport and synthesize GSH, to determine how these functions change with age, and to better understand the role of GSH in the RPE defense against oxidative injury. The ability of RPE cells to transport GSH will be measured by he uptake of radiolabelled GSH. GSH transport will be characterized further by the study of the sodium dependence, pH dependence, concentration dependence, and specificity of the transport system. RPE synthesis of GSH will be measured by using HPLC determination after depletion of intracellular GSH with diethyl maleate (DEM) followed by incubation of cells with radiolabelled amino acid precursors of GSH. The rates of GSH transport and synthesis can be measured and compared with donor age. Further insight into the role of GSH in macular degeneration will be provided by with measurement of cell viability by trypan blue exclusion. Cultured cells will then be supplemented by GSH or the amino acid precursors to determine which better protects the RPE from oxidative injury. By understanding glutathione's role in protecting the retinal pigment epithelium from oxidative injury, these studies will provide insights into the pathogenesis of AMD and, possibly, suggest therapeutic direction for this devastating disease.