MECHANISMS OF RETINAL PHOTOTOXICITY

长期目标：识别-并最终控制- 视网膜照射后形成细胞毒分子(S) 可见光，导致感光细胞退化。这个 正在测试的理论机制是基于脂质的概念 过氧化和对人体有害的中间体的形成 光感受器细胞，在一定条件下，对 视网膜色素上皮(RPE)。具体目标：1)量化 亚油酸和二十二碳六烯酸的过氧化氢和醛 已经在视网膜和光感受器细胞中被鉴定出来 将这项研究扩展到其他重要的多不饱和脂肪酸产品 在光敏细胞中；2)合成质量标记分子 气质联用测定过氧化产物的标准；3) 量化光照射引起的多不饱和脂肪酸变化；4)确定 细胞内过氧化初级和次级产物的细胞毒性 体外和体内；5)确定营养维生素E和A， 硒或类胡萝卜素能够调节产品的生产 PUFA氧化的影响；6)评估抗氧化剂代谢状态 光敏细胞还原含量的测定 谷胱甘肽--维生素E和C，以及谷胱甘肽的活性水平 超氧化物歧化酶和谷胱甘肽过氧化物酶。 为了实现这些目标，白化病和有色鼠将被 维持AIN-76A配方日粮作为对照日粮或 调整到特定的营养水平，以评估其效果 关于脂质过氧化。育儿室的照明将是周期性的 (10L：14D)，强度约为25fC。暴露量 方案将是以下方案之一：1)在1000 FC，3-8小时，2) 连续2-4天在200 FC，或3)连续2-6周在 25FC。冷冻干燥的视网膜将被显微解剖成：“完整的 视网膜，“神经视网膜，光感受器细胞，外节，RPE， 脉络膜。将使用每一层的样本进行分析 多不饱和脂肪酸、过氧化产物或抗氧化剂的GC或GC- 女士将使用传统的生化程序进行评估 特定的细胞酶和谷胱甘肽。结构分析 将包括光学显微镜和电子显微镜。 可能实际上每个人都会受到亚临床症状的影响。 视网膜受损。出现每日累积的光损害 因营养不足和长期暴露而加重 到光(即，电照明)。这项工作旨在 了解视网膜光毒性变性的基本机制 为了更好地评估其重要性并开通航线 控制它，从而保持视网膜健康。

Long-term objective: to identify--and eventually control--the cytotoxic molecule(s) formed on irradiation of the retina with visible light, causing photosensitive cells to degenerate. The theoretical mechanism being tested is based on the concept of lipid peroxidation and the formation of intermediates that are toxic to the photoreceptor cells and, under certain conditions, to the retinal pigment epithelium (RPE). Specific aims: to 1) quantitate hydroperoxides and aldehydes of linoleic and docosahexaenoic acids that have been identified in the retina and photoreceptor cells and extend this research to products from other significant PUFAs found in photosensitive cells; 2) synthesize mass-labeled molecules as standards for quantifying peroxidation products by GC-MS; 3) quantitate PUFA change resulting from photic exposure; 4) determine cytotoxicity of primary and secondary products of peroxidation in vitro and in vivo; 5) determine if nutritional vitamins E and A, Se, or carotenoids are able to modulate the production of products of PUFA oxidation; 6) assess the antioxidant-metabolic state of the photosensitive cells by determining their content of reduced glutathione--vitamins E and C, and the level of activity of superoxide dismutase and glutathione peroxidase. To accomplish these aims, albino and pigmented rats will be maintained on the AIN-76A formulated diet as a control diet or adjusted to specific levels of nutrients to evaluate their effect on lipid peroxidation. Rearing room illumination will be cyclical (10L:14D) with an intensity of approximately 25 fc. Exposure regimens will be one of the following: 1) 3-8 hrs at 1000 fc, 2) 2-4 days continuously at 200 fc, or 3) 2-6 weeks continuously at 25 fc. Freeze-dried retinas will be microdissected into: "whole retina," neural retina, photoreceptor cells, outer segments, RPE, and choroid. Samples of each layer will be used for the analysis of PUFAs, products of peroxidation or antioxidants by GC or by GC- MS. Traditional biochemical procedures will be used to evaluate specific cellular enzymes and glutathione. Structural analysis will include light and electron microscopy. It may be that virtually everyone is subject to subclinical light damage to their retinas. Daily accumulated light damage appears to be aggravated by nutritional deficiencies and extended exposure to light (i.e., electric illumination). This work seeks to understand the basic mechanisms of retinal phototoxic degeneration in order to better evaluate its importance and to open routes to control it, thus preserving retinal health.