方法：选择60只SD大鼠随机分为空白对照组、模型组、PEDF组各20只，除空白对照组外，均建立视神经夹伤大鼠模型，均取左侧眼球为标本，造模成功后，模型组玻璃体腔内注射平衡盐溶液5μL，PEDF组玻璃体内注射5μL PEDF(浓度0.2μg/μL)。2wk后取视网膜组织，行HE染色后光镜下观察视网膜形态的变化，采用比色法测定NO含量的变化，采用逆转录-聚合酶链式反应(RT-PCR)法、蛋白印迹法(Western-blot)检测Caspase-3 mRNA和蛋白表达情况。

结果：HE染色发现，空白对照组视网膜组织排列整齐且清晰，视网膜神经节细胞(retinal ganglion cells，RGCs)呈单层细胞排列，细胞为卵圆形，大小均匀，分布均匀，细胞核清晰，排列紧密，边界清晰； 模型组视网膜组织结构稀疏，RGCs呈空泡样变化，整体细胞数量减少，残留RGCs细胞核见固缩，染色不均。PEDF组视网膜组织残留神经节细胞轻微水肿，但RGCs细胞层排列尚且紧密，且受损程度明显轻于模型组； 模型组、PEDF组Caspase-3 mRNA和蛋白水平高于空白对照组，差异有统计学意义(P<0.05)； PDEF组Caspase-3 mRNA和蛋白水平低于模型组，差异有统计学意义(P<0.05)。模型组、PEDF组NO含量高于空白对照组，差异有统计学意义(P<0.05)； PEDF组NO含量低于模型组，差异有统计学意义(P<0.05)。

结论：采用PEDF干预可下调视神经损伤大鼠Caspase-3、NO的表达，减轻RGCs细胞损伤。

METHODS: A total of 60 SD rats were randomly divided into the blank control group, model group and PEDF group, with 20 rats in each group. Except the blank control group, the optic nerve crush injury rat models were established in the other groups, and left eyeballs were taken as samples. After successfully modeling, the model group were treated with intravitreal injection of 5μL of balanced salt solution while PEDF group were treated with intravitreal injection of 5μL of PEDF(0.2μg/μL). Two weeks later, the retinal tissues were collected, and changes of shape were observed under microscope after HE staining. The changes of NO level were measured by colorimetry assay, the expression of caspase-3 mRNA and caspase-3 protein was detected by reverse transcription-polymerase chain reaction(RT-PCR)and Western-blot.

RESULTS: HE staining showed that retinal tissues of the blank control group arranged neatly and clearly. Retinal ganglion cells(RGCs)arranged in a monolayer, and cells were oval, uniform in size and distribution, the cell nuclei were clear, closely arranged, with clear boundaries. The retinal tissues of the model group were sparse in shape, RGCs showed vacuolar changes, the overall number of cells was reduced, and cell nuclei of residual RGCs showed pyknosis and uneven staining. RGCs in PEDF group were with slightly edema and arranged closely, and the degree of injury was significantly milder than that in the model group. Levels of Caspase-3 mRNA and protein and NO levels in the three groups showed the model group > PEDF group > blank control group(all P < 0.05).

CONCLUSION: The application of PEDF can down regulate the expression of Caspase-3 and NO in rates with optic nerve injury and reduce RGCs injury.