Abstract: ObjectiveTo investigate the intensity of degrading plasma fibrinogen(FIB) and the therapeutic effectiveness of defibrase on treating cerebral ischemia by different administrated ways. MethodsIntraluminal suture method was used to develop reversible middle cerebral artery occlusion (MACO). 154 healthy male Wistar rats were randomized into 2 groups. The rats in intravenous treatment group were injected defibrase intravenously at 0.5,3,6,9,12hours after MACO,while the rats in coeliac treatment group were injected defibrase by abdominocentesis. Meanwhile the control group received normal saline. All rats were killed at 24 hours after MCAO. The thrombus in middle cerebral artery (MCA) and cerebral infarction were examined microscopically in HE stained sections. Infarction volume was measured by using 2,3,5-triphenyltetrazolium chloride staining. 24 rats were selected randomly and injected defibrase by intravenous injection and abdominocentesis. Plasma FIB was measured before and after injection 1,3,6,12,24h by intravenous haemospasia. ResultsPlasma FIB was significantly reduced in intravenous treatment group, and it was lowerest in 3h after intravenous treatment.Clinical Neurological Deficits Scale and infarction volume was significantly reduced in intravenous treatment group than saline control group and coeliac treatment group.There was improvement in Clinical Neurological Deficits Scale in coeliac treatment group compared with that of saline control group, but there was no statistically significant differences at infarction volume.Clinical Neurological Deficits Scale and infarction volume was statistically significant differences in intravenous treatment group at 0.5,3 hours after MCAO. There were no statistically significant differences in intravenous treatment group at 6, 9,12 hours after MCAO.Conclusions Defibrase can reduce the infarction volume in cerebral ischemia early stage.

Key words: focal cerebral ischemia, defibrase, infarction volume