Conserved aquaporin 4 levels associated with reduction of brain edema are mediated by estrogen in the ischemic brain after experimental stroke

► Vasogenic edema of the ischemic brain was reduced in female mice compared males. ► AQP4 levels in the ischemic cortex were maintained in female mice. ► Down-regulated AQP4 levels by ovariectomy were reversed by estrogen replacement. ► An ERs antagonist reduced AQP4 levels with an increase of vasogenic edema. ► Estrogen receptors may regulate AQP4 levels to prevent the ischemic brain edema.