Abstract:

To observe the effect of transcranial ultrasound enhanced thrombolysis by urokinase on expression of matrix metal loproteinase9(MMP9)during cerebral Infarction in rats  and  to study the role of MMP9 in thrombolysis. MethodsAnimal models of acute cerebral infarction were made by injecting autothrombsis into the left middle cerebral artery of male Wistar rats. Intravenous urokinase and transcranial ultrasound were given in 3 hours. Function of the nervous system was measured by NSS. The infarct volume was measured after TTC staining. MMP9 changes were observed by immunohistochemical staining. ResultsThe NSS score of the large dose urokinase group and the ultrasound plus small dose urokinase group at 24 hours after treatment were lower than that before treatment (t=12.59, t=15.31, P<0.01). The infarct volume of the urokinase group and the ultrasound plus small dose urokinase group were lower than that of the infarct group（F=125.99, q=18.02， q=20.62， P<0.01）,but there were no differences between them(q=2.59,P>0.05). There were no positive cells of MMP9 in the shamoperated group. The positive rate and optical density value of MMP9 in the urokinase group or the ultrasound plus urokinase group were more than those in the infract group（F=78.92, F=209.14,P<0.01）.There were no significant differences between  them（q=2.86, and 2.47, P>0.05）.ConclusionTranscranial low frequency ultrasound enhanced thrombolysis by urokinase can accelerate the recovery of the nervous symptoms in acute cerebral infarction rats, diminishes the infarct volume  and reduces the dosage of urokinase. MMP9 participates in thrombolysis of cerebral ischemia and plays an important role  in