Fluoxetine protects neurons against microglial activation-mediated neurotoxicity

Neuroinflammation is closely associated with the pathogenesis of Parkinson's disease (PD) and other neurological disorders. Increasing evidence suggests that inhibition of microglia-mediated neuroinflammation might represent a promising therapeutic potential for PD and related disorders. Fluoxetine, a selective serotonin reuptake inhibitor, is commonly used for the treatment of major depression due to its tolerability and safety profiles. Recent studies have shown that fluoxetine affords robust neuroprotection in a series of neurological disease models. However, the mechanism underlying fluoxetine-mediated neuroprotection remains unclear. Here, by using rat primary midbrain neuronglia cultures, we report that both R and S enantiomers of fluoxetine attenuated chronic neurodegeneration induced by a common inflammogen lipopolysaccharide (LPS) and a neurotoxin 1-methyl-4-phenylpyridinium (MPP(+)). Reconstituted cell culture studies further revealed that microglia were required for fluoxetine-mediated neuroprotection. Fluoxetine significantly inhibited LPS-induced activation of microglia and subsequent release of multiple pro-inflammatory and cytotoxic factors including tumor necrosis factor-α, interleukin-1β, nitric oxide, and reactive oxygen species. Furthermore, inhibition of microglial NF-κB signaling pathway participated in fluoxetine-mediated neuroprotection. Collectively, fluoxetine exerted neuroprotection against microglia-mediated neurotoxicity. Thus, fluoxetine might hold a potential to retard inflammation-mediated chronic neurodegenerative process of PD.