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目的:利用N-甲基-D-天冬氨酸(NMDA)诱导的正常眼压青光眼小鼠模型,研究NMDA与视网膜神经节细胞(RGCs)损伤的关系。方法:6周龄C57BL/6J小鼠随机分为低、中、高三个剂量组,玻璃体腔内分别注射NMDA 10,20,30nmol,产生视网膜损伤动物模型。在整体动物水平通过眼底照相、视网膜电图(ERG);在组织学水平通过视网膜HE染色、视神经甲苯胺蓝染色、全视网膜铺片Brn-3a免疫荧光染色及RGCs计数观察术后6h,12h,24h,48h,7dRGCs的损伤情况。结果:NMDA干预后24h,RGCs数量明显减少,内丛状层厚度变薄。眼底视网膜呈苍白色改变,血管迂曲痉挛;ERG显示a波和b波潜伏期的变化不大,b波振幅下降。光镜下可见RGCs密度逐渐降低;视神经轴索呈退行性变,与NMDA的作用时间呈正相关。RGCs计数显示NMDA诱导的RGC减少主要集中于术后1d,24hRGCs数量减少83.97%(P<0.01)。结论:玻璃体腔内注射NMDA可在不影响眼压的情况下诱导RGCs的显著减少和功能损害,与急性青光眼性损伤具有相似性,可为视神经保护研究提供研究条件。
OBJECTIVE: To study the relationship between NMDA and retinal ganglion cells (RGCs) injury by using a normal intraocular pressure (IOP) mouse model induced by N-methyl-D-aspartate (NMDA). Methods: Six-week-old C57BL / 6J mice were randomly divided into three groups: low dose, middle dose and high dose. The rats were injected with NMDA 10, 20 and 30 nmol intravitreally respectively to induce retinal damage. At the level of whole animal, fundus photography and electroretinography (ERG) were performed. At the histological level, retinal HE staining, toluidine blue staining, Brn-3a immunofluorescence staining and RGCs counting were observed at 6h, 12h, 24h, 48h, 7dRGCs injury. Results: After 24 h NMDA treatment, the number of RGCs decreased significantly and the thickness of the inner plexiform layer became thinner. Fundus retina showed pale color change, blood vessels tortuous spasm; ERG showed a and b wave changes in the incubation period is not big, b wave amplitude decreased. Light microscopy showed RGCs density gradually decreased; optic nerve axons degeneration, and the role of NMDA time was positively correlated. The number of RGCs showed that the decrease of RGCs induced by NMDA mainly focused on the number of RGCs decreased by 83.97% (P <0.01) on the 1st day after operation. CONCLUSION: Intravitreal injection of NMDA can induce significant reduction and dysfunction of RGCs without affecting intraocular pressure, which has the similarities with acute glaucomatous injury and may provide the research conditions for optic nerve protection.