Study on Molecular Mechanism and Therapy of Light-induce Retinal Damage

目的.探讨谷胱甘肽过氧化物酶（GPX）在视网膜光暴露后不同时间点被诱导表达，并定位于不同的视网膜细胞的假说。在实验前，大鼠保持周期性光照2周。在暴露于强烈的白色荧光之前和之后，将动物维持在12小时的光照和黑暗循环中长达24小时，然后返回循环光照。GPX的表达通过荧光细胞化学、Western和北方印迹法测定。光诱导的视网膜损伤通过相对于总视网膜厚度的外核层（ONL）厚度来确定。在周期性光照条件下，正常视网膜的光感受器内节未见GPX标记，而在光感受器外节或视网膜色素上皮（RPE）细胞中观察到轻微的GPX标记。在光下保持12和24小时的视网膜标本中，在感光细胞外节中诱导GPX标记 ...更多信息 RPE细胞。GPX在视网膜色素上皮中的高表达持续到攻击后第7天。与此相反，GPX在感光细胞外节的表达下降，在第1天和第3和第7天曝光后消失。从内界膜到扇形细胞层可见GPX的强标记。GPX标记在高强度白色光和循环条件下均不断定位，表明在这些区域中没有GPX的诱导。此外，GPX标记在视网膜后极处明显，但在周边视网膜处不明显。我们观察到保持在高强度白色光下的大鼠GPX mRNA显著上调。高强度白色光照射后1、3和7 d，对照组和实验组的外核层厚度与整个视网膜厚度的比值有显著性差异（P<0.0001）。高强度白色光照射后不同时间点均可诱导GPX的表达，并定位于不同的视网膜细胞。光暴露后GPX表达的变化可能与视网膜光损伤易感性的差异有关。少

PURPOSE. To examine our hypothesis that glutathione peroxidase (GPX) is induced at different time points after retinal light exposure and localizes in different retinal cells.METHODS. The rats were kept cyclic light for 2 weeks before the experiments. The animals were maintained in 12-hour cycles of light and dark before and after exposure to intense white fluorescent light for as long as 24 hours and then returned to cyclic light. GPX expression was measured by immunohisto-cytochemistry, Western, and Northern blots. Light-induced retinal damage was determined by the outer nuclear layer (ONL) thickness relative to the total retinal thickness.RESULTS. GPX labeling was not seen in the photoreceptor inner segments and slight labeling was observed in the photoreceptor outer segments or the retinal pigment epithelial (RPE) cells in the normal retina kept in cyclic light. In retinal specimens maintained in light for 12 and 24 hours GPX labeling was induced in the photoreceptor outer segments … More and RPE cells. High GPX expression in the retinal pigment, epithelium was sustained until day 7 after challenge. In contrast, GPX expression in the photoreceptor outer segments decreased on day 1 and disappeared on days 3 and 7 after exposure. Intense GPX labeling was seen from the internal limiting membrane to fan lion cell layer. GPX labeling was constantly localized in both high-intensity white light and cyclic conditions, suggesting no induction of GPX in those areas. In addition, GPX labeling was apparent at the posterior retinal pole but not at the peripheral retina. We observe marked upregulation of GPX mRNA in rats kept in high-intensity white light. One, 3 and 7 days after exposure to high-intensity white light, there was a significant difference (P<0.0001) between the control and experimental groups in the ratio of the outer nuclear layer thickness to the entire retina.CONCLUSIONS. GPX was Induced at different time points after exposure to high-intensity white light and localized in different retinal cells. Changes in GPX expression after light exposure may, be related to the difference in light-damage susceptibility of the retina. Less