MECHANISMS OF RETINAL PHOTOTOXICITY

长期目标：查明并最终控制 视网膜照射后形成的细胞毒性分子 可见光，导致感光细胞退化。 的 理论机制是基于脂质的概念 过氧化作用和形成的中间体是有毒的， 感光细胞，在某些条件下， 视网膜色素上皮（RPE）。 具体目标：1）定量 亚油酸和二十二碳六烯酸的氢过氧化物和醛 已经在视网膜和感光细胞中发现， 将这项研究扩展到其他重要PUFA的产品， 在光敏细胞中; 2）合成质量标记分子， 通过GC-MS定量过氧化产物的标准品; 3） 定量由光暴露引起的PUFA变化; 4）确定 过氧化的初级和次级产物的细胞毒性， 体外和体内; 5）确定是否营养维生素E和A， 硒或类胡萝卜素能够调节产品的生产 PUFA氧化; 6）评估抗氧化剂代谢状态， 通过测定光敏细胞中还原型 谷胱甘肽-维生素E和C，以及活性水平， 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，将对白化病和有色大鼠进行 维持AIN-76 A配制饮食作为对照饮食，或 调整到特定的营养水平，以评估其效果 对脂质过氧化的影响 饲养室照明将是周期性的 (10L：14 D），强度约为25 fc。 暴露 方案将是以下之一：1）在1000 ℃下3-8小时，2） 2-4在200 fc下连续2 - 6天，或3）在200 fc下连续2-6周， 25 fc. 冷冻干燥的视网膜将被显微切割成： 视网膜，神经视网膜，感光细胞，外节，RPE， 和脉络膜。 每层的样品将用于分析 PUFA、过氧化产物或抗氧化剂，通过GC或GC- 女士 传统的生化程序将用于评估 特定的细胞酶和谷胱甘肽。 结构分析 将包括光学和电子显微镜。 事实上，每个人都可能受到亚临床光的影响。 对他们的视网膜造成伤害。 每日累积光伤害出现 营养不良和长期暴露于 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， 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.