星形胶质细胞水通道蛋白-4在高渗液中的表达变化

目的研究高渗培养液对体外培养星形胶质细胞表达水通道蛋白-4(Aquaporin-4,AQP4)的影响及AQP4在高渗性脱水中的作用.方法取生后2 d的Wistar大鼠的大脑皮层进行星形胶质细胞纯培养,分别予不同程度的高渗培养液作用于星形胶质细胞,建立星形胶质细胞对高渗液反应的实验模型.通过形态学观察、PT-PCR、免疫细胞化学、四甲基偶氮唑蓝(MTT)比色法及图像分析等方法,研究体外星形胶质细胞对高渗液的反应及AQP4 mRNA和蛋白的表达变化.结果高渗组各时相点吸光度A值均低于对照组(P＜0.05),星形胶质细胞表现出特征性的细胞脱水形态学变化,AQP4mRNA和蛋白的表达均显著高于对照组(P＜0.01),尤以作用12 h后最明显,而且AQP4 mRNA和蛋白的表达呈显著正相关(rs＞0.8485,Ps＜0.01).结论在高渗状态下,AQP4 mRNA和蛋白的表达增强,AQP4表达上调在高渗性脱水的早期(＜12 h)可能起到重要的代偿作用.

Changes of astrocytes Aquaporin- 4 expression in hypertonic medium

Objective To study the effect of hypertonic medium on expression of aquaporin-4 in cultured astrocytes and the role of aquaporin-4 in the course of hypertonic dehydration.Methods Rat cerebral cortical astrocytes obtained from 2-day newborn Wistar rat underwent the pure culture and its model of cell dehydration was established by exposure to hypertonic medium. The reactivity and effect on expression of AQP4 mRNA and protein of astrocytes to hypertonic medium were studied by morphological changes, RT-PCR, immunocytochemistry, MTT and imaging analysis.Results The OD values (MTT) of astrocytes cultured for 3, 6, 12, 24 h with hypertonic medium(320, 333 and 345 mmol/L) were significantly lower than those in the control group( P <0.05), meanwhile, microscope showed typical features of cell dehydration. Immunocytochemistry and RT-PCR analysis confirmed that the expression of AQP4 protein and mRNA was markedly increased than those in the control group ( P <0.01), especially expression of AQP4 was significantly increased with hypertonic medium for 12 hours. The AQP4 mRNA expression showed a positive relationship with the AQP4 protein expression when astrocytes were cultured with hypertonic medium for 1 day ( r_s >0.8485, P_s <0.01).Conclusion The expression of AQP4 mRNA and protein increased in hypertonic medium, which indicated that the up-regulated expression of AQP4 may play an important compensation at the early stage of the hypertonic dehydration.