水通道蛋白4在缺氧缺糖后水肿星形胶质细胞中的作用

Role of aquaporin 4 in swollen rat astrocytes after oxygen-glucose deprivation

目的探讨水通道蛋白4(aquaporin4,AQP4)在缺氧缺糖培养后水肿星形胶质细胞中的表达变化与作用。方法星形胶质细胞分为正常组和缺氧缺糖组,缺氧缺糖组细胞经过5h缺氧缺糖后恢复正常条件培养至0.5、2、8、24h和48h5个时间点时,用光镜观察细胞形态变化,RT-PCR及免疫荧光法测定AQP4的mRNA及蛋白的表达变化。结果①在缺氧缺糖后0.5h,细胞肿胀逐渐形成并继续加重,2h肿胀达到高峰,至8h和24h时肿胀逐渐消退,48h细胞基本恢复正常形态。②RT-PCR和免疫荧光检测:在缺氧缺糖后0.5h,AQP4mRNA和蛋白的表达均较正常组明显下降(P<0.05),2h回升,8h明显超过正常水平,达最高值(P<0.05),24h有所下降,但仍明显高于正常水平(P<0.05),至48h时mRNA和蛋白的表达均基本恢复正常水平。结论缺氧缺糖后星形胶质细胞水肿形成及消退期AQP4的不同表达变化可能都是细胞的一种自身保护机制,从而尽量维持细胞的正常形态和功能。

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.