The Changes Of VEGF And AQPs Gene And Protein Expression In Brain Vascular Endothelial Cells And Astrocytes During Hypoxic Encephaledema

Aim: The changes of VEGF and AQPs gene and protein expression during hypoxic encephaledema and its relation to the changes in blood-brain barrier were investigated in order to elucidate brain injury caused by acute hypoxic exposure, pathogenesis of the encephaledema, and provide the experimental evidence. Methods: Thirty-two male Wistar rats (weighted 350±30g) were randomly divided into 4 groups, i. e. normoxic group and acute hypoxic groups (n=8 for each group). Rats in acute hypoxic groups were exposed to hypoxia at simulated altitude of 4000m, 6000m and 8000m above sea level for 8 hours respectively in order to establish hypoxic encephaledema model. The water content in brain was determined by dry-wet weight method. The occurrence of the encephaledema, the distribution of water in brain, and the apparent diffusion coefficient(ADC) were monitored by diffusion- weighted imaging (DWI). The changes in morphology of brains were observed under high power microscope. The changes of VEGF and AQPs gene and protein expression were determined by RT-PCR and immunohistochemistry. The ultrastructural change of blood-brain barrier was investigated by using an electron microscope. Results: ①The results determined by dry-wet weight method indicated that water content of rats brain increased markedly after rats were exposed to a simulated altitude at 6000m, 8000m, and the amplitude of increase in water content was dependent on the hypoxic extent. ②After rats were exposed to acute hypoxia, abnormal low intensity signals were occurred in DWI, ADC values increased significantly in the hypoxic groups exposed to 6000m or above, and the increasing amplitude of ADC values was dependent on the hypoxic extent. ③The results determined by light microscopy indicated that...