Cellular and regional specific changes in multidrug efflux transporter expression during recovery of vasogenic edema in the rat hippocampus and piriform cortex

In the present study, we investigated the characteristics of drug efflux transporter expressions following status epilepticus (SE). In the hippocampus and piriform cortex (PC), vasogenic edema peaked 3-4 days after SE. The expression of breast cancer resistance protein (BCRP), multidrug resistance protein-4 (MRP4), and p-glycoprotein (p-GP) were decreased 4 days after SE when vasogenic edema was peaked, but subsequently increased 4 weeks after SE. Multidrug resistance protein-1 (MRP1) expression gradually decreased in endothelial cells until 4 weeks after SE. These findings indicate that SE-induced vasogenic edema formation transiently reduced drug efflux pump expressions in endothelial cells. Subsequently, during recovery of vasogenic edema drug efflux pump expressions were differentially upregulated in astrocytes, neuropils, and endothelial cells. Therefore, we suggest that vasogenic edema formation may be a risk factor in pharmacoresistent epilepsy.