Objective    To study the expression of aquaporin 4（AQP4）in swollen astrocytes after oxygen-glucose deprivation (OGD).     Methods    Astrocytes primarily cultured from 2-day-old  SD rats were divided into normal group and OGD group. Five hours after OGD

the cells were cultured for 0.5

2

8

24 and 48 h in normal culture medium

respectively. Morphological alterations of astrocytes were observed under a light   microscope. Expression of AQP4 mRNA and protein in astrocytes was detected by RT-PCR and immunofluorescence assay

respectively.     Results    Swelling of astrocytes occurred in 0.5 h after OGD

reached its peak in 2 h after OGD

gradually disappeared in 8-24 h after OGD

and became almost normal in 48 h after OGD. RT-PCR and immunofluorescence assay showed that the expression level of AQP4 mRNA and protein in astrocytes began to decrease

increase and return to normal

respectively

in 0.5

8

and 48 h after OGD.     Conclusion    The expression level of AQP4 is decreased in swollen astrocytes in 5 h after OGD possibly by preventing the entry of it-mediated water into astrocytes

and is increased during the recovery stage of cell swelling by promoting excretion of water from swollen astrocytes.