Dexamethasone treatment modulates aquaporin-4 expression after intracerebral hemorrhage in rats

This study investigated whether dexamethasone (DEX) treatment could regulate the expression of aquaporin-4 (AQP4) in rats with intracerebral hemorrhage (ICH). The results demonstrated that DEX significantly reduced AQP4 mRNA level in the perihematomal area compared with control group, but it increased the level in the brain area surrounding the third ventricle at day 1 post-ICH. There was no difference in AQP4 protein levels between DEX group and control group at the two above-mentioned brain regions at day 1 after ICH. The changes in AQP4 protein induced by DEX were marked at day 3 following surgery and still lasted at day 5 post-ICH, which were accompanied by a reduction of brain edema. Our results demonstrated that the expression of AQP4 protein after ICH was region-specific, time-dependent, and also indicated that DEX-induced cerebral edema clearance was correlated with the regulation of AQP4 expression in different brain regions.