Abstract: Objective: To establish the rat diabetic models by introperitoneal injection of streptozotocin(STZ) to observe the expressions of MMP-2 in retina tissue of the diabetic rats at different periods,and to clarify the effect of MMP-2 in the diabetic retiropathy(DR) of the diabetic rats. Methods: The femal SD rats were divded into normal control group(n=24), 4-week model group(n=30), 6-week model group(n=30) and 8-week model group(n=30).The rats in model groups were intraperitoneally injected with STZ for consecutive 5 d.The rats in normal control group were injected with sodium citrate solution at the same volume. The body weights and blood glucose levels of the rats in each group were measured at 4,6, and 8 weeks.The retina of each rat was removed; RT-PCR and Western blotting methods were used to detect the expression levels of MMP-2 mRNA and protein,and the immunohistochemistry was conducted to observe the morphology. Results: The body weights and blood glucose levels of the rats in each group had no differences(P>0.05) before modeling.Three rats died in 4-week model group, 5 rats died at 6 weeks and 7 rats died at 8 weeks.The body weights of the rats in model group were significantly lower than those in normal control group at the same time(P<0.05 or P<0.01),and the fasting blood glucose levels were signifieantly increased(P<0.05 or P<0.01).The expression levels of MMP-2 mRNA and protein in the retina tissue of the rats in model group were significantly higher than those in normal control group(P<0.05). In normal control group, the retinal structure was clear and the cells were arranged in order, and the ganglion cells were arranged in a single layer; in model group, the retinal tissue structure was loose, the number of ganglion cells were significantly reduced,the inner nuclear layer and rod cell layer cell membrane outside were fuzzy. The MMP-2 positive cells were found to be brown yellow granules, especially in the cytoplasm of ganglion cells and vascular endothelial cells. The positive expression levels of MMP-2 in model group were higher than those in normal control group at 4,6,and 8 weeks. Conclusion: MMP-2 can express in the retina tissue of the diabetic rats.

Key words: matrix metalloproteinase-2, streptozotocin, diabetic retinopathy