Abstract: Objective To investigate the change of arginine-vasopressin V1α receptor（V1αR）and aquaporin 4(AQP4) expression，to explore the mechanism of brain edema caused by intracerebral hemorrhage（ICH）．Methods Autologous blood were injected into the caudate nucleus to establish ICH models in rats．The changes of brain water content (BWC)were measured by wet and dry weight methods．The expression of V1αR and AQP4 were detected by immunofluorescence and Western blot after 6、12、24 and 48h．Results The expression of V1αR and AQP4 increased at 6h after ICH，and significantly increased the peak at 48h（21.88±0.44 and 23.16±0.67）than the sham group（14.32±0.55 and 13.90±0.40）．V1αR and AQP4 expressions positively correlated with BWC（P＜0.05）．Conclusion The increased expression of AQP4 mediated by V1αR played an important role in the brain edema after ICH．

Key words: arginine-vasopressin, V1a receptor, aquaporin 4, brain edema