Objective:To study the biologic effects of various concentrations of thrombin on aquaporin 4(AQP4)expression in rat primary cultured astrocytes,and to explore the regulation mechanism of transmembrane water transportation in astrocytes after intracerebral hemorrhage(ICH).Methods:Primary cultured astrocytes were incubated in culture mediums containing various concentrations of thrombin for 24 h and harvested.AQP4 mRNA and AQP4 protein expression were determined by reverse transcription polymerase chain reaction(RT-PCR)and immunohistochemical technique.Cell apoptosis was detected by TdT-mediated dUTP nick end labeling(TUNEL)technique.Cell morphology was observed by phase contrast microscope,and cell viability was assayed by MTT.Results:AQP4 mRNA and AQP4 protein showed a low expression in normal astrocytes.The expression of AQP4 mRNA and AQP4 protein significantly increased in the astrocytes treated with 100 U/ml or 200 U/ml thrombin(P < 0.01),and these astrocytes swelled.The number of TUNEL positive cells significantly increased.On the other hand,AQP4 mRNA and AQP4 protein expression were down-regulated in the astrocytes treated with 0.5 U/ml or 1 U/ml thrombin(P < 0.05),and the cell morphology did not change.Few TUNEL positive cells were observed.Conclusion:AQP4 over-expression induced by high concentrations of thrombin causes an increased permeability of water in astrocytic membrane.On the contrary,the decreased AQP4 expression prevents the astrocytes from swelling and apoptosis. Objective: To study the biologic effects of various concentrations of thrombin on aquaporin 4 (AQP4) expression in rat primary cultured astrocytes, and to explore the regulation mechanism of transmembrane water transportation in astrocytes after intracerebral hemorrhage (ICH). Methods: Primary cultured astrocytes were incubated in culture mediums containing various concentrations of thrombin for 24 h and harvested. AQP4 mRNA and AQP4 protein expression were determined by reverse transcription polymerase chain reaction (RT-PCR) and immunohistochemical technique. Cell apoptosis was detected by TdT-mediated dUTP nick end labeling (TUNEL) technique. Cell morphology was observed by phase contrast microscope, and cell viability was assayed by MTT. Results: AQP4 mRNA showed a low expression in normal astrocytes. The expression of AQP4 mRNA and AQP4 protein significantly increased in the astrocytes treated with 100 U / ml or 200 U / ml thrombin (P <0.01), and these astrocytes swelled.The number of T UNQ positive cells were significantly increased. On the other hand, AQP4 mRNA and AQP4 protein expression were down-regulated in the astrocytes treated with 0.5 U / ml or 1 U / ml thrombin (P <0.05), and the cell morphology did not change. FeW TUNEL positive cells were observed. Conlusion: AQP4 over-expression induced by high concentrations of thrombin causes an increased permeability of water in astrocytic membrane. On the contrary, the decreased AQP4 expression prevents the astrocytes from swelling and apoptosis.