OBJECTIVETo study the dynamic expression of protease-activated receptor-1(PAR-1) after acute intracerebral hemorrhage (ICH) and the influence of Naomai capsule (NMC II) on the expression in rats.

METHOD72 rats were randomly divided into 9 groups (n = 8 in each group). They were normal group, ICH model groups at 6, 24 h, 3, 7 d and NMC II groups at 6, 24 h, 3, 7 d. ICH models were induced by 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 at different groups.

RESULTPAR-1 protein and mRNA were mild positive in normal group. In model groups, intensity of PAR-1 expression started to enhance at 6 h, and enhanced more at 24 h. PAR-1 expression reached the peak at 3 d and began to descend. At 7 d the decent was obvious. At 6, 24 h, 3, 7 d time point. The PAR-1 protein positive cell number and PAR-1 mRNA absorbance ratio in ICH model and NMC II groups were significantly higher than those in normal group (P < 0.05 or P < 0.01). The PAR-1 protein positive cell number and PAR-1mRNA absorbance ratio in NMC II group were significantly lower than those in ICH model group (P < 0.05 or P < 0.01).

CONCLUSIONAfter ICH, PAR-1 is continuously activated because of the simulation of thrombin. Function of thrombin after ICH maybe mediated by PAR-1; NMC II may inhibit the expression of PAR-1. This may be one of the main therapeutics mechanisms of NMC II.