一种改良的光诱导视网膜分级损伤大鼠模型

背景大鼠视网膜光损伤动物模型因诸多影响因素较难复制，使不同因子（如药物）对视网膜光损伤生物学效应的研究受到影响。目的改良大鼠视网膜光损伤动物模型的制作方法，建立大鼠视网膜光损伤程度分级模型。方法选用8～10同龄雄性SD大鼠24只，根据强光暴露时间的不同将动物按随机数字表法分为正常对照组和光损伤1、2、3h组，每组6只大鼠。为获得眼球的全视野光辐照，采用环形光照箱将LED灯集中分布在光照箱的上下和光照箱四周共8个方向，保证大鼠在光照箱内做单向环形活动时其右眼接受约5000lx的光照。实验中每只动物单独接受光辐照，以避免动物之间的相互干扰。光辐照后5d进行全视野视网膜电图（ERG）记录，并进行常规组织病理学观察，评价视网膜外核层（ONL）的厚度变化。结果5000lx强光暴露1、2、3h后暗适应条件下的ERG视杆细胞反应、标准光最大混合光反应的b波幅值分别下降了26．2％、52．5％、70．7％和24．4％、39．3％、58．1％，OPs波、视锥细胞反应、20Hz闪烁光反应也均有明显下降，不同光照时间组间各波平均振幅值的总体差异均有统计学意义（视杆：F=71．690，P=0．000；混合光反应：F=56．250，P=0．000；OPs：F=23．610，P=0．000；视锥：F=27．130，P=0．000；20Hz：F=27．030，P=0．000）；不同光照时间组间各波平均隐含时的总体差异均有统计学意义（视杆：F=1．370，P=0．282；混合光反应：a波：F=0．800，P=0．508；b波：F=11．840，P=0．000；视锥：F=2．080，P=0．136）。振幅下降及隐含时延长的程度均与光暴露时间有关。视网膜的光损伤以视网膜颞上区域明显，光辐照1、2、3h后该区域ONL厚度较正常对照组分别减少了11．3％、25．6％、72．5％，各组的平均ONL厚度随光照时间的延长逐渐变薄，差异有统计学意义（F=410．270，P=0．000）。结论光强度为5000lx连续光辐照后可以造成大鼠视网膜损伤，光辐照1、2、3h后损伤程度分为轻、中、重3级，主要损伤部位在大鼠视网膜颞上区域。研究提出了一种视网膜光损伤程度标准的建议。

An improved model of light-induced retinal damage for grading standardization in rat

Background Light-induced retinal damage models vary as many influence factors,herein the modeling method is difficult to copy.It is necessary to establish the grading standardization of retinal damage after retinal light exposure.Objective This study was to improve the modeling method and establish a grading standardization for light-induced retinal damage in rat.Methods Twenty-four SPF 8-10 week-old male SD rats were randomly divided into 4 groups and 6 eyes for each group.The rats were exposed to light intense of 5000 lx for 1,2,3 hours respectively in 3 groups,and other 6 rats served as the normal group.Full-field light exposure experiment was performed for each individual rat separately,and an annular illumination box was used tO ensure the experimental rat moving in a single direction and exposing the right eye in 5000 lx light surrounding during experimental duration.Ganzfeid electroretinogram(ERG)was recorded from the experimental rats at the fifth day after light exposure,and the animals were then sacrificed for histopathology observation to evaluate the retinal thickness change.All procedures which involved animals adhered to the ARVO Statement for the Use of Animals in Ophthalmic and Vision Research.Results After exposing to intensity light for 1,2,3 hours,the b-wave amplitudes of rod response,maximal mixed response,oscillatory potential in scotopic ERG as well as cone response,20 Hz flicker response of photopic ERG were significant declined as lapse of light exposure time(F=71.690,P=0.000；F=56.250,P=0.000；F=23.610,P=0.000：F=27.130,P=0.000；F=27.030,P=0.000)and lowed by 26.2％,52.5％,70.7％,24.4％,39.3％,58.1％respectively at the end of experiment.Meanwhile,the b-wave latencies of rod response,maximal mixed response in scotopic ERG as well as cone response of photopic ERG were evidently different among different groups (F=1.370,P=0.282；F：0.800,P=0.508；F=11.840,P=0.000；F=2.080,P=0.136).Light induced retinal damage located mainly at the temporal retina area.After intensity light exposure for 1,2,3 hours,the thickness of outer nuclear layer at the superior temporal retina attenuated by 11.3％,25.6％and 72.5％,respectively(P<0.05).A significant difference was seen in mean thickness of outer nuclear layer at superior temporal retina among different groups(F=410.27,P=0.000). Conclusion A standardized grading method for light-induced retinal damage is recommended.The continuous illumination in a intensity of 5000 Ix for 1,2,3 hours can induce the mild,moderate or severe retinal damage respectively at temporal retina.