Schisandrin B restores M1/M2 balance through miR-124 in lipopolysaccharide-induced BV2 cells

Abstract Background In this study, Schisandrin B (SCHB), the main active component of Schisandra chinensis extract (SCE), was taken as the research object. From gene, microRNA (miR-124), and the level of protein expression system to study the influences of microglia phenotype to play the role of nerve inflammation. Methods In this study, we investigated the role of miR-124 in regulating microglial polarization alteration and NF-κB/TLR4 signaling and MAPK signaling in the LPS-induced BV2 by PCR, western blot, ELISA, immunofluorescence, and cytometry. Results SCE and SCHB significantly reduced the NO-releasing, decreased the levels of TNF-α, iNOS, IBA-1, and ratio of CD86+/CD206+, and increased the levels of IL-10, Arg-1. In addition, SCE and SCHB inhibited the nucleus translocation of NF-κB, decreased the expressions of IKK-α, and increased the expressions of IκB-α. Besides, the expressions of TLR4 and MyD88, and the ratios of p-p38/p38, p-ERK/ERK, and p-JNK/JNK were reduced by SCE and SCHB treatments. Furthermore, SCHB upregulated the mRNA levels of miR-124. However, the effects of SCHB were reversed by the miR-124 inhibitor. Conclusions These findings suggested SCHB downregulated NF-κB/TLR4/MyD88 signaling pathway and MAPK signaling pathway via miR-124 to restore M1/M2 balance and alleviate depressive symptoms.