Severe Burns In Brain Tissue Of Aqp4, Aqp9 In The Expression And Regulation Mechanism

Objective: The aim of this study was to investigate the rule of aquaporin-4(AQP4) and aquaporin-9(AQP9) expression in the stage of brain edema after severe bum and to clarify the cause of brain edema.Methods: Heathy Wistar rats (n=90,W=250~300g) were divided into 2 groups randomly, control group(n=15) and bum group(n=75). The bum group (30%TBSA, III degree) was subdivided into 5 groups at an interval of 2 h, 6 h, 12 h, 24 h and 48 h. The brain tissues of the rats in each group were examined respectively: The brain water content(BWC) was measured by dry-wet Weight methods; The sections of bum brain were stained with HE to study pathological changes; Immunohistochemistry (ICC) and In Situ Hybridization (ISH) methods were used to study AQP4 AQP9 and their mRNA expressions. After that the imaging analysis of the AQP4 AQP9 and their mRNA expression was made by means of Computer-aided Image Analyzer.Results: The brain water content of the rat was improved since 2h severe bum, it reached the peak time at 6h. HE staining showed that the brain tissuehad swelling changes after severe burn. The space around neurons glial and capillary became larger, the number of neurogliocyte increased, several cell nucleies were deeply dyed. The expression of AQP4 and AQP9 in rat brain tissue after severe burn is stronger than that in the control group. The AQP4 and AQP9 positive cells were located in the choroid plexes ependyma hippocampus supraoptic nucleus paraventricular nucleus and other brain areas. The AQP4 and AQP9 were distributed in the cytomembrane, but not stained in the cytoplasm and nuclei. The protein expression reached a peak at 6h. The distribution of signal ISH was as same as IHC, but in ISH the positive staining was detected at the cytomembrane and cytoplasm. The expression of AQP4 AQP9 was significant positive correlated with its mRNA during the brain edema formation. The expression of AQP4 AQP9 was correlated with BWC respectively after severe burn.Conclutions: The brain water content of the rats gradually improved and the brain tissue had swelling changes after severe burn, It indicted that the brain edema appeared. The expressions of AQP4 AQP9 and their mRNA up-regulated in brain tissue after severe burn. The BWC and the expression of AQP4 AQP9 reached a peak at the same time after severe burn 6h. The results indicate that AQP4 and AQP9 may play an important role in the formation and development of brain edema after severe burn.