Defense mechanism for age-related macular degeneration.

锰超氧化物歧化酶(Mn-SOD)是一种天然存在的清除活性氧中间体之一的超氧化物歧化酶。为确定在强光照射等氧化应激条件下，大鼠眼球中锰超氧化物歧化酶的表达是否增强，将大鼠暴露于强光(1800lux)2周，再暴露于强光(1800lux)24小时后，分别在光照后3小时、1天、3天、7天和14天摘除实验眼和对照眼的眼球，用兔抗大鼠锰超氧化物歧化酶的抗血清进行免疫组织化学染色，观察大鼠视网膜外核层厚度与对照组的差异无统计学意义。实验动物视网膜色素上皮(RPE)细胞和光感受器内节段均进行了MnSO4标记，光刺激后3h和1d，视网膜色素上皮(RPE)细胞和感光器内节段重新表达；光刺激后3h和1d，视网膜色素上皮(RPE)细胞和感光器内节段重新表达。这些结果提示视网膜对光损伤可能具有保护作用，其中锰-超氧化物歧化酶可能起着重要作用。

Manganese superoxide dismutase (Mn SOD) is a naturally occurring scavenger of superoxide, one of reactive oxygen intermediates. To determine if Mn SOD expression is enhanced as a defensive mechanism against oxidative challenges, such as intense light exposure, rats were exposed to cyclic tight (80 lux) for 2 weeks, intense light (1,800 lux) for 24 hours, and then again to cyclic light, Experimental and control (exposed to cyclic light only) eyes were enucleated 3 hours, 1, 3, 7, and 14 days after light challenge and protein expression was examined immunohistochemically using rabbit antisera against rat Mn SOD.There was no significant difference between the light-exposed and the control groups in the thickness of the outer nuclear layers. Both retinal pigment epithelial (RPE) cells and photoreceptor inner segments in the normal retina were labeled for Mn SOD.After Mn SOD labeling was lost 3 hours and day 1 after light challenge, it was re-expressed in the RPE cells days 3, 7, and 14 and in the photoreceptor inner segments the day 14 after light challenge in experimental animals. These results suggest that the retina might have a protective potential against light damage, in which Mn-SOD may play some important role.