Effect of metformin on release of inflammatory factor from LPS-stimulated microglia and its possible mechanism

WANG Haiyan; ZHANG Junfeng; GUO Yong; JIA Peiyu; WANG Xuemin

doi:10.3969/j.issn.1002-266X.2016.42.001

Abstract：Objective To observe the effect of metformin on the release of inflammatory factor from lipopolysaccharide (LPS)-stimulated microglia and to investigate the possible mechanism.Methods The cytotoxicity of metformin to BV2 cells in logarithmic growth phase was tested by Trypan blue exclusion.Then BV2 cells were randomly divided into LPS stimulation group (LPS group,cells were cultured with LPS in 50 ng/mL for 24 hours)and LPS plus Metformin group (ob-servation group,cells were cultured with metformin in 0.02,2,8,and 16 mmol/L for 24 hours first,then cultured with LPS in 50 ng/mL for 24 hours).TNF-αwas detected by ELISA.The proliferation was calculated by Cell counting.The cell viability was tested by MTT.The cell cycle was evaluated by propidium iodide staining +flow cytometry.The apoptot-ic rate was analyzed by improved propidium iodide staining +flow cytometry.Results The microglia treated with differ-ent concentrations of metformin refused staining of the trypan blue exclusion.Compared with LPS group,metformin de-creased the level of TNF-α,inhibited the proliferation of microglia and increased the apoptotic rate in a dose-dependent manner (P <0.05,0.01,0.01 at 2,8,and 16 mmol/L respectively).With the increased metformin concentration,the percentage of microglia in the G1 phase was increased.Significant difference was found in the percentage of microglia in the G1 phase between the LPS group and observation group with 8 and 16 mmol/L (P <0.05,P <0.01).Conclusion Met-formin decreases the release of inflammatory factor from LPS-stimulated microglia,and the mechanism may be related to the inhibition of microglia proliferation and promotion of microglia apoptosis.