Fluoxetine affords robust neuroprotection in the postischemic brain via its anti-inflammatory effect

Fluoxetine is a selective serotonin reuptake inhibitor that is widely used in the treatment of major depression including after stroke. In this study, we tested whether fluoxetine protects neuronal death in a rat cerebral ischemia model of middle cerebral artery occlusion (MCAO). The administration of fluoxetine intravenously (10 mg/kg) at 30 min, 3 hr, or 6 hr after MCAO reduced infarct volumes to 21.2+/-6.7%, 14.5+/-3.0%, and 22.8+/-2.9%, respectively, of that of the untreated control. Moreover, the neuroprotective effect of fluoxetine was evident when it was administered as late as 9 hr after MCAO/reperfusion. These neuroprotective effects were accompanied by improvement of motor impairment and neurological deficits. The fluoxetine-treated brain was found to show marked repressions of microglia activation, neutrophil infiltration, and proinflammatory marker expressions. Moreover, fluoxetine suppressed NF-kappaB activity dose-dependently in the postischemic brain and also in lipopolysaccharide-treated primary microglia and neutrophil cultures, suggesting that NF-kappaB activity inhibition explains in part its anti-inflammatory effect. These results demonstrate that curative treatment of fluoxetine affords strong protection against delayed cerebral ischemic injury, and that these neuroprotective effects might be associated with its anti-inflammatory effects.