AIMTo study the dynamic and long-lasting expression of thrombin receptor after acute intracerebral hemorrhage (ICH) in rats.

METHODS36 rats were randomly divided into 6 groups (n = 6): Normal group and ICH model groups at 6 hours, 24 hours, 3 days, 7 days and 14 days. ICH models were produced with the induction of collagenase type VII-S. Immunohistochemical method was used to detect PAR-1 protein and RT-PCR technique was used to detect PAR-1mRNA in brain tissue around the haematoma in different groups.

RESULTSPAR-1 protein and mRNA were mild positive in normal group. In model groups, intensity of PAR-1 expression started to enhance at 6 hours, and enhanced more at 24 hours. PAR-1 expression reached the peak at 3 days and began to descend. At 7 days the descent was obvious and there was further descent at 14 days. At each time point, the PAR-1 protein positive cell number and PAR-1mRNA absorbance ratio in ICH model groups were significantly higher than those in normal group (P < 0.05 or P < 0.01). In addition, PAR-1 proteins were obviously expressed in vivo in brain capillary endothelial cell.

CONCLUSIONFunctional PAR-1 exists in brain capillary endothelial cells. Activation of PAR-1 after ICH due to the stimulation of thrombin is not only the initiating agent of cerebral edema after ICH, but also participates the development of cerebral edema.