Rat model of intracerebellar hemorrhage.

Approximately 15% of all strokes are due to intracerebral hemorrhage (ICH) and of these, 5-10% occur in the cerebellum. The resultant mortality is around 20-30%. However, there is no well-established animal model to address this important clinical problem. We induced intracerebellar hemorrhage in rats using stereotaxic collagenase injection through a burr-hole into right cerebellum. Dosage-dependent effect of collagenase (0.2, 0.4, and 0.6 U) was tested in male and female rats. Brain edema formation was assessed by brain water content and hemorrhagic volume measured by hemoglobin assay. Wire suspension, inclined plane, beam walking, and neurological deficit score assessed neurological outcome. Marked hematoma was observed in right cerebellum, accompanied by brain edema in a dose-related fashion. When comparing sexes, hemorrhagic volume and neurological deficit scores were significantly increased in females compared to male counterpart. Females had mortality of 16%, while there was no mortality in male rats. Neurological deficits assessed by both beam walking and inclined plane were significantly increased at 0.4 and 0.6 U in females, but only at 0.6 for males. This new cerebellar hemorrhage rat model demonstrated dosage- and sex-dependent changes in hemorrhagic volume, brain edema, and neurological deficits, and could be used to test treatment strategies for ICH.