Diammonium glycyrrhizinate negatively regulates LPS-induced neuroinflamma-tory responses in BV2 microglia via TLR4/NF-κB signaling pathway
Objective:To evaluate effect of diammonium glycyrrhizinate(DG)on lipopolysaccharide(LPS)-induced TLR4/NF-κB inflammatory signaling pathway in BV2 microglial cells and to explore its potential regulatory mechanisms on ameliorating neu-roinflammation.Methods:BV2 microglia injury model was induced by LPS and treated with 20 and 60 μmol/L DG.MTS was used to determine vitality of cells.NO level secreted by cells was detected by Griess.Inflammatory factors TNF-α,IL-6,and IL-1β levels in cell supernatant were measured by ELISA.TNF-α,IL-6,IL-1β,TLR4 and MyD88 mRNA levels were detected by RT-qPCR.Western blot was used to determine expressions of TLR4,MyD88,NF-κB,p-NF-κB,IκB-α and p-IκB-α proteins of cells.Results:Compared with control group,LPS-treated BV2 microglia had significantly lower viability(P<0.05),significantly higher NO secretion(P<0.05),significantly up-regulation levels of inflammatory factors TNF-α,IL-6 and IL-1β(P<0.05),and significantly higher mRNA levels of TNF-α,IL-6,IL-1β,TLR4 and MyD88(P<0.05),TLR4,MyD88,NF-κB,p-NF-κB,IκB-α,and p-IκB-α protein expressions were significantly increased(P<0.05).Compared with LPS group,BV2 microglia intervened with different concentrations of DG had significantly higher viability(P<0.05),significantly lower NO secretion(P<0.05),significantly lower TNF-α,IL-6 and IL-1β inflammatory factors levels(P<0.05),significantly lower mRNA levels of TNF-α,IL-6,IL-1β,TLR4 and MyD88(P<0.05),and TLR4,MyD88,p-NF-κB and p-IκB-α protein expressions were significantly reduced(P<0.05).Conclusion:DG can inhibit LPS-induced neuroinflammatory responses in microglia,whose underlying mechanism is suppression of TLR4/NF-κB signaling pathway.
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