Figure 7

Paroxetine suppresses the lipopolysaccharide (LPS)-stimulated pro-inflammatory cytokines and nitric oxide (NO) in primary microglial cells. (A) Purity assessment of isolated primary microglial cells. Cells were immunostained with ani-Iba-1 antibody (red) and Hoechst 33258 for nuclei (blue). (B) Cell viability analysis. Cells were treated with 0, 2.5, 5, 7.5 or 10 μM of paroxetine for 24 hours. Cell viability was expressed relative to the control (0 μM), which was set as 100%. Values are means ± SE of three independent experiments. *P < 0.05 versus the control. (C) Effect of paroxetine on TNF-α and IL-1β productions. For cytokine release in media (the upper panel), cells were pretreated with paroxetine for 30 minutes and then stimulated with LPS at 100 ng/ml for 24 hours. *P < 0.05 versus treated with LPS alone. For mRNA expression (the lower panel), cells were pretreated with 7.5 μM paroxetine for 30 minutes followed by LPS treatment at 100 ng/mL for six hours. The mRNA levels of each cytokine were quantified and normalized with their respective β-actin. Each value was expressed relative to the one treated with LPS alone, which was set as 100. *P < 0.05; values are means ± SE of four independent experiments. (D) Effect of paroxetine on NO production (the upper panel) and inducible nitric oxide synthase (iNOS) expression (the lower panel). Cells were pretreated with paroxetine for 30 minutes and then stimulated with LPS at 100 ng/ml for 24 hours. The iNOS protein levels were quantified and normalized with their respective β-actin. Each value was expressed relative to the one treated with LPS alone, which was set as 100. *P < 0.05 versus treated with LPS alone. Values are means ± SE of four independent experiments. PAR, paroxetine; LPS, lipopolysaccharide; NO, nitric oxide; iNOS, inducible nitric oxide synthase.