Objective:To investigate the changes in expression of Aquaporin-9(AQP9) in the hippocampus of mouse model of Alzheimer’s disease(AD). Methods:APPswe/PS1 d E9 double transgenic male mice aged 9 months(n=12)and C57 wild-type(WT)male mice aged 9 months(n=12)were used as model of AD and control

respectively. Morris water maze tests were used to assess the learning and memory abilities of animals. Immunohistochemical staining

Western blot and q RT-PCR were applied to exam the expression of AQP9 protein and its m RNA in the hippocampus of the AD model and WT mice. Results:The water maze test showed that AD model mice took longer latency and had significantly less platform-passing times than WT mice(t=7.064

P=0.000). The results of immunohistochemical staining showed that the absorbance(A)value of AQP9 immunoreactivity in different hippocampus areas were increased in the hippocampus of the AD model mice compared with in that of the WT mice(CA1:t=7.373

P=0.000;CA2:t=3.1

P=0.011;CA3:t=4.428

P=0.001;girus:t=5.285

P=0.000). The results of Western blot showed that the expression of AQP9 protein were increased compared with in that of the WT mice(t=5.305

P=0.003). The q RT-PCR showed that AQP9 m RNA were increased in the hippocampus of the AD model mice compared with in that of the WT mice(t=3.646

P=0.045). Conclusion:AQP9 protein and its m RNA are upregulated in the hippocampus of the APPswe/PS1 d E9 double transgenic mice model of AD.