The Research On The Relationship Of Angiostatin, Matrix Metalloproteinase-9 And Vascular Endothelial Growth Factor In The Brain Of Type 2 Diabetic GK Rats After Transient Middle Cerebral Artery Occlusion

OBJECTIVES:To establish a model of acute cerebral ischemia-reperfusion in diabetic rats;To observe the expression of angiostatin and vascular endothelial growth factor and the activity of MMP-9 in the cerebral ischemic tissues;To research the relationship between the expression of angiostatin and the activity of MMP-9;To investigate the involvement of VEGF,angiostatin and MMP-9 in the brain of type 2 diabetic GK rats after transient focal cerebral ischemia.METHODS:(1) Diabetes groups[Goto-Kakizaki(GK) rats]and respective control groups (Wistar rats) were divided randomly into 3 groups:the sham-operated group,cerebral ischemic groups(CI) and cerebral ischemic rats complicated with diabetes groups(DM+CI).The model of MCAO is established in the DM+CI group and CI group,and the two groups were randomly assigned to 4 subgroups according to the reperfusion time(3h,24h,72h,168h);(2) The assessment standard of Langa'5 scores was applied to assess the neural function of the rats after cerebral ischemia-reperfusion;(3) Western blotting and SDS-PAGE zymography were used to estimated the protein expressions of angiostatin and VEGF and the activity of MMP-9 at different I/R time point.The absorbance of the band was measured by AlphaEase FC Imagine software;(4) The results were expressed as(?)±s,The SPSS13.0 statistic software was used in analying the results by ANOVA,q test and linear correlation analysis.RESULTS:(1) The assessment results of the rats' neural functions The awaked rats from CI group and DM+CI group after operation appear Horner's signs;It was assessed successfully that showing bending the left forelimb,turning left,or falling toward left. While the sham-operation group displayed Horner's signs only;(2) Expression of Angiostatin protein low-level expression can be found in the sham-operation,and the absorbance of the band increased over time in DM+CI and CI group(p＜0.05 or 0.01).However,at different I/R time point,angiostatin expression showed similar patterns in DM+CI and CI group:increased at 3h,maximized at 24h, and then decreased gradually,but still above the normal level at 168h.There was a significant increase of protein expression in DM+CI group compared with that in CI group at 24h and 168h(p＜0.05);(3) Expression of VEGF protein Similar with the expression of angiostatin,the expression level of VEGF increased at all reperfusion time in both CI and CI+DM groups.At the same reperfusion time,angiostatin expression in CI+DM group is higher than that of CI group(p＜0.05 or 0.01);(4) Activity of MMP-9 the activity of MMP-9 in ischemic brain tissue were upregulated;started to increase at 3h after reperfusion,reached its peak at 24h and then decreased gradually,but still stayed more than the basal level at 168h;The activity of MMP-9 was more significantly increased in the DM+CI group than in the CI group at all I/R time points(p＜0.01);(5) A correlation study demostrated that there was a linear correlation between angiostatin expressions and MMP-9 activity in the DM+CI group(r=0.8833,p＜0.05) and the CI group(r=0.8894,p＜0.05). CONCLUSIONS:(1) Expressions of VEGF and angiostatin and activity of MMP-9 were upregulated in the ischemic brain tissues after I/R,indicating that VEGF,angiostatin and MMP-9 involed in the pathological courses of cerebral ischemia;(2) There were significantly lower expressions of VEGF paralleled with higher expression of angiostatin and MMP-9 in the ischemic tissues after ischemia-reperfusion complicated with diabetes than without it.It suggested that hyperglycemia may play roles in their expressions;(3) The coherence between angiostatin expressions and MMP-9 activity in the DM+CI group and CI group indicated that there was a relationship between the increased expressions of angiostatin and the enhanced activity of MMP-9 in the ischemic tissues;...