AIM: To analyze the effect of pigment epithelium derived factor(PEDF)on nitrogen monoxide(NO)and expression of cysteine-containing, aspartate-specific proteases-3(caspase-3)in retinal tissues of model rats with optic nerve crush injury.

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.