短暂清除小胶质细胞减缓光诱导损伤小鼠视网膜视功能退变

目的：探讨小胶质细胞在急性光诱导小鼠视网膜损伤中的保护作用。方法：实验研究。将30 只雄性ICR白化小鼠随机均分为对照组、光损伤组和小胶质细胞清除组。对照组不进行任何处理；光损伤组在15 000 lx白光下照射20 h；小胶质细胞清除组在白光照射前先持续5 d腹腔注射小分子抑制剂PLX5622，随后经15 000 lx白光照射20 h，继续注射3 d PLX5622后于次日取材。所有动物在取材当日，先运用视网膜电图（ERG）检测视网膜功能，随后摘取眼球，OCT包埋眼杯，进行冷冻切片，或者剥离视网膜。运用免疫组织化学和TUNEL染色等方法观察小鼠视网膜损伤程度及小胶质细胞的形态和功能。实验数据采用单因素方差分析进行比较。结果：运用15 000 lx白光照射白化小鼠20 h，可获得视网膜功能损伤和光感受器凋亡的稳定模型。ERG反应的a、b波振幅统计结果显示，光损伤组光感受器和双极细胞出现功能障碍，且TUNEL阳性细胞较对照组多（P=0.035），激活的小胶质细胞亦明显较多（P<0.001）。免疫组织化学结果显示，清除小胶质细胞组外核层和外网状层的小胶质细胞较光损伤组少（P=0.027），CtBP2信号和PKC-α信号较强，外节长度维持在正常水平（P<0.001），但ERG反应b波振幅和TUNEL阳性细胞差异无统计学意义。结论：清除小胶质细胞可以在短期内减少光感受器细胞凋亡，并挽救视网膜功能。

Transient Depletion of Microglia Attenuates Light-Induced Retinal Degeneration in Mice

Objective: To investigate the protective effect of microglia on acutely light-induced retinal degenerationin the mouse. Methods: This was an animal experimental study. Thirty male ICR mice were randomlydivided into a control group, light-damaged group and a microglia depletion group. The control group didnot receive any treatment. The light-damaged group was exposed to 15 000 lx white light for 20 hours. Themicroglia depletion group was intraperitoneally injected with the small molecule inhibitor PLX5622 for 5days before white light irradiation, followed by 15 000 lx white light irradiation for 20 hours, and then thePLX5622 injection was continued for 3 more days. Retinal function was measured by the electroretinogramon day 5 after light exposure. Then the eyes were removed, and the eye cup or whole-mount retina wasprepared. Immunohistochemistry and TUNEL staining were used to observe the degree of retinal damageand the morphology and function of microglia. The experimental data were analyzed by one-way analysisof variance (ANOVA). Results: In this study, mice were exposed to 15 000 lx white light for 20 hours toobtain a stable model of retinal dysfunction and photoreceptor apoptosis. The amplitudes of the a and bwaves of the ERG response showed that photoreceptors and bipolar cells were dysfunctional in the lightdamaged group, and TUNEL positive cells increased significantly compared to the control group (P=0.035).Activated microglia also increased significantly (P<0.001). Immunohistochemical results showed thatmicroglias in the outer nuclear layer and outer plexiform layer were significantly reduced in the microgliadepletion group compared to the light-damaged group (P=0.027). The CtBP2 signal and PKC-α signalwere enhanced, and the outer segment length remained at a normal level (P<0.001), but there was nostatistically significant differences between the ERG response b wave amplitude and TUNEL positive cells.Conclusion: The depletion of microglia can reduce photoreceptor apoptosis and save retinal function in thevery short term.