Anti-neuroinflammatory mechanism of safinamide in inhibiting lipopolysaccharide-induced microglial activation

Neuroinflammation is an inflammatory response in the central nervous system that may lead to neurodegenerative diseases, such as Parkinson’s disease (PD). PD is the second most common neurodegenerative disorder with a high prevalence among elderly individuals. Microglia, which are associated with neuroprotection, are activated during inflammation, resulting in damage to dopaminergic neurons in the substantia nigra. Based on previous studies, safinamide can provide neuroprotection to dopaminergic neurons by inhibiting microglial activation. Hence, this study aims to investigate the anti-neuroinflammatory mechanism of safinamide in inhibiting lipopolysaccharide (LPS)-induced microglial activation. 2,5-diphenyl-2H-tetrazolium bromide (MTT) assay was used to evaluate the cytotoxicity of safinamide on BV-2 (microglial) cells. Maximum non-toxic dose (MNTD) and half MNTD of safinamide were then calculated. To determine whether safinamide could rescue lipopoly-saccharide-treated BV-2 cells from cell death and oxidative stress, MTT assay and dichloro-dihydro-fluorescein diacetate (DCFH-DA) assay were performed, respectively. Enzyme-linked immunosorbent assay (ELISA) was performed to investigate the involvement of STAT1/NF-kappa B pathway proteins in the activation of microglia. The MNTD of safinamide was determined to be 29.5±10.66 µM. Safinamide was not able to rescue BV-2 cells from LPS-induced cell death. Nevertheless, a slight reduction of reactive oxygen species levels was noted when LPS-induced BV-2 cells were treated with safinamide. There was a slight decrease in protein expression of STAT1, NF-kappa B, iNOS and COX-2 in the LPS-induced BV-2 cells after treatment with safinamide. While safinamide did not rescue BV-2 cells from cell death, safinamide has been shown to slightly reduce oxidative stress in BV-2 cells.