ANTIOXDANT SYSTEMS AND AGE-RELATED MACULAR DEGENERATION

视网膜相关性黄斑变性（AMD）是导致失明的主要原因 在60岁以上的美国人口中。 现有证据表明 AMD是由视网膜色素功能的恶化引起的， 上皮（RPE）。 RPE在光感受器中的关键作用 碎片消化，RPE的富光和富氧位置 它为氧化损伤提供了环境， 的荧光色素的RPE与老化可能刺激 氧化过程联合收割机表明氧化损伤是一种潜在的 AMD的原因 抗氧化系统保护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，其通过与以下物质反应而起到抗氧化剂的作用： 自由基和过氧化物来限制非酶氧化过程。 通过这种解毒作用，GSH在保护机体免受 在许多细胞系统中来自化学品或其它来源的氧化损伤， 包括肝肺和肾 初步研究已经 证明外源性GSH可以保护培养的人RPE细胞免受 氧化损伤 本提案的目的是描述 RPE运输和合成GSH的能力，以确定如何 这些功能随着年龄的增长而变化，为了更好地了解GSH的作用， 在RPE防御氧化损伤中的作用。 RPE细胞转运GSH的能力将通过摄取来测量。 放射性标记的谷胱甘肽 GSH转运将进一步表征为 钠依赖性、pH依赖性、浓度依赖性 运输系统的特殊性。 视网膜色素上皮细胞合成谷胱甘肽 在细胞内GSH耗尽后使用HPLC测定来测量 用马来酸二乙酯（DEM）孵育细胞， 放射性标记的GSH的氨基酸前体。 GSH转运率 和合成可以被测量并与供体年龄进行比较。 进一步深入了解谷胱甘肽在黄斑变性中的作用， 通过台盼蓝排除法测量细胞活力。 然后将培养的细胞补充GSH或氨基酸 前体，以确定哪种更好地保护RPE免受氧化损伤 损伤 通过了解谷胱甘肽在保护视网膜色素中的作用 这些研究将为我们提供 AMD的发病机制，并可能提出治疗方向 这种毁灭性的疾病。

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.