Bolus injection of hypertonic solutions for cerebral edema in rats: Challenge of homeostasis of healthy brain

► Bolus injection of HS (3% NaCl) and 20% mannitol effectively dehydrates rat brain with edema. ► HS and mannitol injection activates microglia in healthy hemisphere in different degrees. ► HS compromises BBB more mildly than mannitol at the same time course. ► Bolus injection of HS and mannitol leads to cellular edema around the brain capillaries. ► Both HS and mannitol down-regulate AQP4 expression in the healthy brain without changing its distribution.