光照对大鼠视网膜的影响及其机制研究

Effect of light on the rat retina and its mechanism

目的探究光损伤对大鼠视网膜结构和功能的影响及其机制。方法自制光照箱。取健康成年SD(Sprague-Dawley)雄性大鼠,随机分为正常组和实验组。正常对照组大鼠饲养在12 h明12 h暗的正常环境中;实验组大鼠首先暗适应24 h,后采用5000 lx照度的可见光照射48 h,再暗适应24 h。麻醉大鼠,时间约30 min。首先,应用视网膜电生理(ERG)检测大鼠视网膜功能;其次,取出大鼠眼球后放入眼球固定液或4%多聚甲醛,制作石蜡切片行苏木精-伊红(HE)染色观察视网膜组织结构变化,冰冻切片行TUNEL染色,分别应用光镜和共聚焦显微镜观察。实时荧光定量反转录聚合酶链反应(qRT-PCR)及蛋白质印迹法(WB)检测光损伤后视网膜肿瘤坏死因子-α(TNF-α)含量。结果HE染色显示光照后视网膜外核层较正常明显变薄,颞侧较鼻侧视网膜损伤较重;TUNEL染色显示光损伤后视网膜凋亡细胞数量明显增多;qRT-PCR及WB显示光损伤后视网膜组织表达TNF-α增多;ERG显示光损伤大鼠视网膜功能明显降低。以上结果差异均有统计学意义(P<0.05)。结论光照后视网膜外核层损伤是导致视网膜功能受损的原因之一,视网膜损伤可能与TNF-α表达增多有关。

Objective To study the effect of strong visible light on the structure and function of the rat retina and its mechanism.Methods Self-made light box.Adult Sprague-Dawley(SD)rats were randomly divided into normal control and experimental groups.Normal control group rats were raised in a normal environment of 12 h light/12 h dark cycle.Rats in the experimental group were first darkly adapted for 24 h,then were irradiated with 5000 lx strong visible light for 48 h,followed by a dark adaption of another 24 h.All the rats were anesthetized for about 30 minutes.Firstly,the retinal function of the rats were detected by retinal electrophysiology(ERG);Secondly,rats'eyeballs were removed and fixed in fixative solution or 4%polyoxymethylene before paraffin or frozen sections were made for HE staining and TUNEL staining respectively.Paraffin sections with HE staining were used to observe the change of retinal tissue structures under light microscope,and frozen sections with TUNEL staining were observed under confocol microscope.qRT-PCR and Western blot(WB)were used to detect tumor necrosis factor-α(TNF-α)content in the photo damaged retinas.Results HE staining showed that retinal outer nuclear layer was significantly thinner than normal after light exposure,and the temporal side was more severely damaged than the nasal side;TUNEL staining showed that the number of retinal apoptotic cells increased significantly after photo damage;qRT-PCR and WB revealed that TNF-αincreased in the photo damaged retinas;and ERG demonstrated that the retinal function of photo damaged rats was significantly reduced.All the results above were statistically different(P<0.05).Conclusions The damage of outer nuclear layer(ONL)after light exposure is one of the reasons for the impairment of retinal function,and the retinal damage may be related to the increased expression of TNF-α.