Abstract: To investigate the involvement of matrix metalloproteinase-9 and the vascular endothelial growth factor in diabetic rat brains during different reperfusion times after focal cerebral ischemia. Methods 120 Wistar rats were randomly divided into 4 groups: the normal control group, the operation control group, the simple cerebral ischemic rats(CI group) and the diabetic cerebral ischemic rats(DM+CI group). Rat models of diabetes mellitus were made by high sucrose， fat diet and streptozotion injection. The models of the middle cerebral artery occlusion were made by an improved zealong′s method. The expressions of MMP-9 and VEGF in the brain tissues were determined by immunohistochemistry staining. ResultsMMP-9 and VEGF mainly distributed in the cytoplasm of neuroglia cells，neurons, some vascular endothelial cells, and in the ischemic penumbra zones of the DM+CI group and the CI group. Along with the reperfusion times，the expressions of the cells changed differently. MMP-9 and VEGF significantly increased in the DM+CI group and the CI group compared with the normal control group (P<0.05).MMP-9 was more significantly increased in the DM+CI group than in the CI group (P<0.05) and peaked at 24h； VEGF was more significantly decreased in the DM+CI group than in the CI group (P<0.01) and peaked at 6?h.　There was a linear correlation between MMP-9 and VEGF expressions in the DM+CI group and the CI group. In the DM+CI group, MMP-9 and VEGF expressions were negatively correlated at 6-24h after reperfusion. ConclusionsThe increase of MMP-9 expression contributes to the decrease of VEGF and it may participate in the pathology of reperfusion of diabetic infarct brains.

Key words: Diabetes mellitus, Gelatinase B, Vascular endothelial growth factor, Extracellular matrix, Infarction, middle cerebral artery, Rat, Wistar