The Study Of Effect Of Inhibiting Matrix Metalloproteinases On Thrombolysis Time Window In Ischemic Stroke

Objective This study is aimed at the effect of urokinase at ifferent time on the expression of matrix metalloproteinase-9 (MMP-9), the permeability of the brain-blood barrier, the infarction volume, the cerebral hemorrhage content and the rate of hemorrhagic transformation after ischemic storke, and evaluating the effect of urokinase and then studying it's complications and corresponding reasons. we also investigated the effect of doxycycline and sanqizaodai on the expression of MMP-9 and other targets. Finally, we studyed whether MMP inhibition affected the thrombolysis time window.Methods A focal cerebral ischemia of rats were established by embolizing left middle cerebral artery with autologous blood clots and the rats were then randomly assigned to ten groups: Group 1, Ischemia control group; Group 2 to 4, urokinase at 6, 9, and 12 hours after ischemia; Group 5 to 7, a combination of doxycycline at 2 hours and urokinase at 6, 9, and 12 hours after ischemia; Group 8 to 10, a combination of sanqizaodai at 2 hours and urokinase at 6, 9, and 12 hours after ischemia. At the 24th hour after ischemia, all rats were killed. The expression of MMP-9 was detected with immunohistochemical staining, the permeability of the brain-blood barrier was observed with Evan's blue and the cerebral hemorrhage was quantified with spectrophotometer assay; pathologic methods and TTC staining were applied to detect pathologic changes of the brain tissue and the infarction volume.Results With urokinase treatment at the 6th hour the expression of MMP-9 was increased and the infarction volume was decreased, but the brain water content,the cerebral hemorrhage content and the permeability of the brain-blood barrier were not obviously changed. And the expression of MMP-9 and the permeability of the brain-blood barrier were obviousely increased and the brain water content, infarction volumes, cerebral hemorrhage content and the rate of hemorrhage transformation were further rised with urokinase thrombolysis at more than 6 hour after ischemic stroke. After urokinase combined with doxycycline or sanqizaodai treatment the expression of MMP-9 was obviousely decreased and the permeability of brain-blood barrie, the brain water and the infarction volume were decreased.Conclusion Our data suggest that after urokinase treatment the expression of MMP-9 and the permeability of the brain-blood barrier were increased, and the level was related to the time of urokinase thrombolysis. The effect of Urokinase thrombolysis was well at 6th hour after ischemic stroke, but there was badly effect with urokinase thrombolysis at more than 6 hour. The complications of urokinase were the breakdown of brain-blood barrie and the cerebral hemorrhage aggravating. The MMPs inhibitor doxycycline or sanqizaodai attenuates urokinase induced the expression of MMP-9, the breakdown of brain-blood barrie, the cerebral edema and the cerebral infarction volume, and it may be enhanced the effect of urokinase thrombolysis, but the thrombolysis time window may be not delayed by MMPs inhibitor.