ANTIOXIDANT SYSTEMS AND AGE RELATED MACULAR DEGENERATION

老年性黄斑变性(ARMD)是导致视力的主要原因 老年美国人的损失。光感受器的损伤会导致 ARMD的失明通常继发于视网膜色素损伤 上皮(RPE)细胞。有大量的间接数据可以证明 支持ARMD可能与氧化损伤有关的假设 RPE细胞表现出疾病的早期迹象。我们现在有了数据 直接表明谷胱甘肽是一种重要的抗氧化剂 保护培养的人RPE细胞免受氧化损伤。此外, 初步研究表明，血浆谷胱甘肽水平随着 ARMD患者可能存在较低的血浆GSH水平。 在本申请中，我们建议进一步定义GSH在 保护RPE免受氧化损伤。两组研究将 用来评估衰老和急性呼吸窘迫综合征对血液谷胱甘肽的影响(L) GSH水平将在一组没有ARMD的患者中被测量为 以及特征良好的ARMD患者，包括 没有服用微量营养素抗氧化剂补充剂的患者，以及2)GSH 综合能力将在不同年龄的捐赠者的眼睛中确定， 通过测定GSH合成率和活性来检测ARMD患者和非ARMD患者 催化谷胱甘肽合成的酶--γ-谷氨酰半胱氨酸合成酶 (GCS)，培养的RPE细胞和新鲜RPE细胞中GCS的mRNA的测定 尸检眼睛的RPE。将进行进一步的研究，以确定 谷胱甘肽合成能力是否可以通过治疗来操纵 不同的GSH前体、激素诱导剂或酚类抗氧化剂 可诱导GCS活性。最后，机械论研究将确立L) 改善细胞内GSH的维持是否会导致 过氧化氢的清除和更好的细胞内维护 抗氧化剂、抗坏血酸和α-生育酚，以及2)外源性GSH 可以通过防止损害两个关键的质膜运输来保护 Na+，K+-ATPase和Ca2+-ATPase系统。 这些研究的结果将提供关键数据，以帮助我们 了解ARMD的发病机制，为进一步研究ARMD提供平台 为未来的治疗做准备。

Age-related macular degeneration (ARMD) is the leading cause of vision loss in elderly Americans. The photoreceptor damage that results in blindness in ARMD is usually secondary to injured retinal pigment epithelial (RPE) cells. There is substantial circumstantial data to support the hypothesis that ARMD may be related to oxidative injury and that RPE cells exhibit early signs of the disease. We now have data directly showing glutathione (GSH) to be an important antioxidant capable of protecting cultured human RPE cells from oxidative injury. In addition, preliminary studies demonstrate that plasma levels of GSH decrease with age and that there may be lower plasma GSH levels in ARMD patients. In this application, we propose to further define the role of GSH in protection of the RPE from oxidative injury. Two groups of studies will be performed to evaluate the effects of aging and ARMD on GSH: l) blood levels of GSH will be measured in a cohort of patients without ARMD as well as those with well characterized ARMD, including a sub-population of patients not taking micronutrient antioxidant supplementation, and 2) GSH synthetic capacity will be determined in eyes of donors of varying ages, with and without ARMD by measuring the rate of GSH synthesis and activity of the enzyme catalyzing GSH synthesis, gamma-glutamycysteine synthetase (GCS), in cultured RPE cells, and by measurement of mRNA for GCS in fresh RPE from autopsy eyes. Further studies will be performed to determine whether GSH synthetic capacity can be manipulated therapeutically using different GSH precursors, hormonal inducers, or phenolic antioxidants that may induce GCS activity. Finally, mechanistic studies will establish l) whether improved maintenance of intracellular GSH leads to increased peroxide elimination and better maintenance of the intracellular antioxidants, ascorbate and alpha-tocopherol, and 2) whether exogenous GSH can protect by preventing damage to two critical plasma membrane transport systems, Na+,K+ATPase and Ca2+-ATPase. The results of these studies will provide critical data to help in our understanding of the pathogenesis of ARMD and could provide the platform for future therapies.