Expression of aquaporin-9 in the brain tissue of rats with infectious brain edema

Abstract

Objective To investigate the expression of aquaporin-9(AQP-9)in the brain tissue of rats with infectious brain edema and explore the role of AQP-9 in the oecurrgnce and progression of the brain edema. Methods A total of 128 normal 1-month-old SD rats weighing 70-100 g of either sex were randomly divided into two equal groups, namely the normal saline(NS) group and lipopolysaecharide(LPS)group.Acute infectious brain edema was induced in rats in the LPS group by injecting LPS via the left internal carotid artery,and the rats in the NS groups received NS injection.At 6,12,24 and 48 h after the injection,the brain tissue was taken from the rats to observe the histopathology by Hernatoxylin-Eosin Stain and lneasure the brain water content(BWC).The permeability of the blood-brain barrier of the rats was tested using Evans blue(EB)method.The expressions of AQP-9 protein and mRNA in the brain tissue Were detected using immunohistochemistry and RT-PCR,respectively. Results InLPS group,the space around the blood vessels was obviously broadened in the brain tissue,where inflammatory cell infiltration,glioeyte swelling,vacuolar degeneration of the neurons and neuronal nuclear shrinkage were seen.At 6,12,24,and 48 h following LPS or NS injection,the BWC,EB content,and expressions of AQP-9 protein and mRNA in the LPS group were all significantly higher than those in the NS group(P<0.05),In the LPS group,positive correlations were found between BWC and EB content,AQP-9 protein expression and BWC,AQP一9 mRNA and BWC,AQP-9mR.NA and EBcontent,and between AQP-9 protein andmRNA.Conclusion AQP-9 might participate in occurrcnce and development of infectious brain edema in rats,it might be positive correlation. Key words: Aquaporin-9; Infectious brain edema; Reverse transeription-polymerase chain reaction