Determining the neuroprotective effects of dextromethorphan in lipopolysaccharide­stimulated BV2 microglia.

Microglial activation has been recognized as being vital in the pathogenesis of several neurodegenerative disorders. Therefore, the identification of therapeutic drugs to prevent microglial activation and thus protect against inflammation­mediated neuronal injury, is required. In the present study, dextromethorphan (DM), a compound widely used in antitussive remedies that has been demonstrated to possess neuroprotective effects, was shown to reduce proinflammatory mediator production in lipopolysaccharide (LPS)­stimulated BV2 mouse microglial cells. Western blot analysis revealed that DM markedly suppressed the activation of nuclear factor­κB (NFκB), caspase­3 signaling and the expression of another inflammation­inducing factor, heat shock protein 60 (HSP60) and heat shock factor­1, induced by LPS in BV2 cells. Results from ELISA assay demonstrated that DM reduced the release of HSP60, nitric oxide (NO), inducible NO synthase, tumor necrosis factor­α, interleukin (IL)­1ß and IL­6 induced by LPS in BV2 microglia. These results were confirmed by immunofluorescence, suggesting that DM may exert a neuroprotective and anti­inflammatory effect by inhibiting microglial activation through the HSP60­NFκB signaling pathway. Therefore, DM may offer substantial therapeutic benefits in the treatment of neurodegenerative diseases that are accompanied by microglial activation.