高原反应的脑病理与水通道蛋白-4(AQP4)的相关性实验研究

目的研究高原反应的脑病理变化及发病机制.方法Wistar大白鼠56只,分正常对照和实验组,实验组进入模拟5 000 m高原环境饲养,取4、24、48 h、3 d、2、4周各组各时相点动物活杀取脑作光、电镜一般形态学观察,硝酸镧示踪血管通透性观察,水通道蛋白(AQP4)和mRNA光、电镜免疫组化和原位杂交,GLU(glutamate,谷氨酸),GABA(gamm-aminobutyric,γ氨基丁酸)含量检测.结果光、电镜观察显示实验组早期(4～72 h)脑毛细血管内皮细胞出现吞饮泡增多、线粒体肿胀、紧密连接松弛、胶质足肿胀以及(24、48 h)硝酸镧漏出血管腔等病理改变,神经细胞无明显病理变化;免疫组化和原位杂交显示AQP4在血管内皮细胞、胶质纤维阳性表达,AQP4 mRNA在毛细血管内皮细胞核和胶质细胞核呈阳性表达,二者的表达情况在实验组早期增高.结论BBB病变是动物进入高原出现较早的病理变化;早期胶质细胞肿胀可能是一种保护性调节;AQP4 mRNA的表达变化可能是调节BBB通透性并维持水平衡的分子机制.

Study of aquaporin protein 4 with cerebral pathology and pathogenesis of high altitude response

Objective To investige the cerebral pathology and pathogenesis of high altitude response. Methods A total of 48 Wistar rats were put into 5 000-meter high altitude environment as experiment groups and another 8 were employed as control. At the time point of 4, 24, 48, 72 h, 2 weeks and 4 weeks, the cerebral morphology of all animals was observed by light microscope and electron microscope, the permeability of blood brain barrier(BBB)was traced by lanthanumLa(NO_(3))_(3).nH_(2)O], the immunolochemistry and hybridization in situ for aquaporin protein 4 (AQP4) and mRNA were performed and glutamate (GLU), gamma-amino butyric acid (GABA) were tested by aminophenol analysis. Results In the early period of 4-72 h, there were enhancing vesicles in endothelial cells, swollen mitochondria, and tight junction relaxation with the leaking of lanthanum nitrate in the endothelial cells, as well as swelling of astrocyte end-feet in the experiment rats. There were no prominent pathologic changes in the neuron. AQP4 immunoreactivity was localized to capillary wall and astrocyte processes. AQP4 mRNA was expressed at nucleus of endothelial cells and astrocytes, and more intense in the experiment rats at the early period. Conclusion The changes of BBB is the early pathologic changes of high altitude response. Swelling of astrocyte could be a way of protective regulation. The changes of AQP4 and AQP4 mRNA expressions may be one of molecular mechanisms in regulating BBB permeability and maintaining water homeostasis.