Acetate Suppresses Lipopolysaccharide-stimulated Nitric Oxide Production in Primary Rat Microglia but not in BV-2 Microglia Cells

Aims: To show that acetate attenuates neuroinflammatory responses in activated microglia. Background: Dietary acetate supplementation alleviates neuroglial activation in a rat model of neuroinflammation induced by intraventricular administration of lipopolysaccharide (LPS). However, the precise mechanism(s) underlying the anti-inflammatory effect of acetate, is not fully understood. Objective: To determine whether acetate has inhibitory effects on LPS-induced neuroinflammatory responses in microglia. Methods: We examined LPS-stimulated nitric oxide (NO) production in primary rat microglia and BV-2 cells. Protein expression of inducible NO synthase (iNOS) was determined by western blot analysis. The intracellular generation of reactive oxygen species (ROS) and glutathione (GSH) were also evaluated. Results: In primary microglia, acetate decreased LPS-stimulated NO production in a dose-dependent manner, reaching significance at greater than 10 mM, and cell viability was not affected. Acetate suppressed LPS-induced expression of iNOS protein concomitantly with the decrease in NO. The LPS-induced increase in intracellular ROS production was attenuated by acetate. In addition, acetate prevented LPS-induced reduction of GSH. Notably, such suppressive effects of acetate on NO and ROS production were not observed in BV-2 cells. Conclusion: These findings suggest that acetate may alleviate neuroinflammatory responses by attenuating NO and ROS production in primary microglia but not in BV-2 cells. Other: All animals received humane care, and the animal protocols used in this study were approved by the Ethics Committees for Animal Experimentation.