Fluoxetine inhibits transient global ischemia-induced hippocampal neuronal death and memory impairment by preventing blood-brain barrier disruption.

Ischemia induces blood-brain barrier (BBB) disruption by matrix metalloproteases (MMPs) activation, leading to neuronal cell death. Here, we show that fluoxetine inhibits apoptotic cell death of hippocampal neuron and memory impairment by blocking BBB disruption after transient global ischemia. Fluoxetine treatment (10 mg/kg) after global ischemia significantly inhibited mRNA expression of MMP-2 and -9 and reduced MMP-9 activity. By Evan blue assay, fluoxetine reduced ischemia-induced BBB permeability. In parallel, fluoxetine significantly attenuated the loss of occludin and laminin in the hippocampal area after ischemia. By immunostaining with occludin antibody, fluoxetine preserved the integrity of vascular networks, especially in hippocampal areas after injury. Fluoxetine also prevented the infiltration of macrophages and inhibited the mRNA expression of inflammatory mediators after injury. In addition, the activation of microglia and astrocyte in hippocampal regions was significantly attenuated by fluoxetine. Finally, fluoxetine reduced apoptotic cell death of hippocampal neurons as well as vascular endothelial cell death and improved learning and memory. Thus, our study suggests that the neuroprotective effect of fluoxetine is likely mediated by blocking MMP activation followed BBB disruption after transient global ischemia, and the drug may represent a potential therapeutic agent for preserving BBB integrity following ischemic brain injury in humans.