MECHANISMS OF RETINAL PHOTOTOXICITY

拟议研究的长期目标是确定-以及 最终控制--细胞毒性分子， 用可见光照射视网膜并引起感光性 细胞退化。 视网膜光毒性的理论机制是 基于脂质过氧化和 对光敏细胞有毒的中间体，在某些情况下， 视网膜色素上皮细胞（RPE），导致他们 堕落 本研究的具体目标是：（1）确定光 视网膜的损伤是通过光敏脂质 氧化;（2）使用视网膜损伤的生物化学标记（即，脂质 氧化中间体）以评估损伤的主要部位（例如， 光感受器vs RPE）;（3）确定是否营养维生素E或维生素A 能够调节视网膜对光损伤的敏感性;（4） 确定脂质氧化的生化标志物是否与 视网膜变性的区域模式;（5）相关的个体动物 光损伤敏感性随生化水平的变化 标记物;和（6）证明特异性脂质氧化的细胞毒性 中间体的 为实现上述目标，将饲养白化病和有色大鼠 含有特定水平维生素E和A的配方饮食， exposure. 将视网膜的冷冻干燥切片显微切割成 三个特定的层：神经视网膜，感光细胞， 视网膜色素上皮脉络膜 将分析每层样品的维生素E， 不饱和脂肪酸和气体过氧化产物 色谱-质谱法（GC-MS）。 结构分析将包括 光学和电子显微镜，以及视网膜电图将用于 评估视网膜功能。 随着人类视网膜组织从新鲜的尸检或手术中获得， 它将用于开发处理小视网膜活检的程序， 为今后可能进行的研究获取关于上述参数的数据库。 事实上，每个人都可能受到亚临床光损伤 到视网膜上。 日积月累的光害似乎加重了 由于营养缺乏和长时间暴露于光（即，电动 照明）。 这项工作旨在了解的基本机制， 视网膜光损伤，以便更好地评估其重要性，并打开 控制它的途径，并保持视网膜健康。

The long-term objective of the proposed research is to identify--and eventually control--the cytotoxic molecule(s) that are formed upon irradiation of the retina with visible light and that cause photosensitive cells to degenerate. The theoretical mechanism of retinal phototoxicity is based on the concept of lipid peroxidation and the formation of intermediates that are toxic to the photosensitive cells and, under certain conditions, to the retinal pigment epithelium (RPE), causing them to degenerate. The specific aims of the proposed research are to (1) determine if light damage to the retina occurs by a mechanism of photosensitized lipid oxidation; (2) use biochemical markers of retinal damage (i.e., lipid oxidation intermediates) to assess primary sites of damage (e.g., photoreceptors vs RPE); (3) determine if nutritional vitamin E or vitamin A are able to modulate the sensitivity of the retina to photic injury; (4) determine if the biochemical markers of lipid oxidation correlate with regional patterns of retinal degeneration; (5) correlate individual animal variation in sensitivity to light damage with levels of biochemical markers; and (6) demonstrate the cytotoxicity of specific lipid oxidation intermediates. To accomplish the above aims, albino and pigmented rats will be maintained on formulated diets containing specific levels of vitamins E and A prior to exposure. Freeze-dried sections of retina will be microdissected into three specific layers: neural retina, photoreceptor cells, and RPE-choroid. Samples of each layer will be analyzed for vitamin E, unsaturated fatty acids, and products of peroxidation by gas chromatography-mass spectrometry (GC-MS). Structural analysis will include light and electron microscopy, and electroretinograms will be used to assess retinal function. As human retinal tissue becomes available from fresh autopsies or surgery, it will be used to develop procedures to handle small retinal biopsies and acquire a data base on the above parameters for possible future studies. It may be that virtually everyone is subjected 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 light damage in order to better evaluate its importance and to open routes to control it, and to preserve retinal health.