The Effect Of Sertraline On TNF-?/NF-?B Signaling Pathway In Microglia Of Depressed Mice

Objective:In this study,we investigated the anti-inflammatory mechanism of sertraline through the NF-?B signaling pathway in mice with chronic unpredictable mild stress(CUMS)in vivo and microglia(BV2)inflammation induced by tumor necrosis factor-a(TNF-a)in vitro.Methods:In vivo experiments,forced swimming test(FST)and tail suspension test(TST)were used to detect the behavioral characteristics of CUMS mice and evaluate the improvement of sertraline on depression;Western blot was used to detect the effect of sertraline on the activation of microglia in the brain tissue of CUMS mice;Western blot was detected the effect of sertraline on the expression of nuclear factor-KB(NF-?B)pathway protein(pNF-?B and pI?B-a)and its downstream inflammatory factors(tumor necrosis factor-?[TNF-?],interleukin-1?[IL-1?]and inducible nitric oxide synthase[iNOS)in the brain tissue of CUMS mice;Enzyme-linked immunosorbent assay(ELISA)was used to detect the effects of sertraline on serum levels of inflammatory factors(TNF-a,IL-1?,NO)and aminotransferase(ALT,AST)in CUMS mice.In vitro,MTS assay was used to detect the effect of sertraline on the survival rate of BV2 cells induced by TNF-a;Western blot was used to detect the effect of sertraline on TNF-a-induced microglia activation;The effect of sertraline on the expression of NF-?B pathway protein(pNF-KB and pI?B-a)and its downstream inflammatory factors(TNF-a,iNOS)in BV2 cells induced by TNF-a was detected by Western blot;Immunofluorescence method was used to observe the effect of sertraline on nuclear heterotopicity of NF-?B.Results:In vivo experiments:The results of behavioral test showed that compared with the control group,the forced swimming and tail-suspension immobility time of the model group mice increased significantly(P<0.05,P<0.01),indicating the accomplishment of modeling,after the treatment of sertraline,behavioral in mice significantly improvement;Western blot results showed that compared with the control group,the expression of Iba-1 in model mice increased significantly(P<0.001),sertraline could reduces the expression of Iba-1 in a dose-dependent manner(P<0.05,P<0.001),suggested that sertraline can inhiibit the activation of microglia induced by CUMS;The results of Western blot and ELISA showed that compared with the control group,the levels of major inflammatory mediators(TNF-a,IL-1p,iNOS(NO))in brain tissue and serum in model group increased significantly(P<0.01),after sertraline treatment,the levels of these inflammatory mediators decreased significantly,suggested that sertraline can inhibit inflammation in central and peripheral blood induced by CUMS,in addition,sertraline also decreased the level of aminotransferase(ALT,AST)in CUMS mice serum,suggested that sertraline has a protective effect on liver injury induced by CUMS;The results of Western blot showed that compared with the control group,the content of pNF-?B and pI?B-a in brain tissue of model group mice increased significantly(P<0.001),sertraline reduced its expression,suggested that sertraline can inhibit the activation of NF-?B induced by CUMS.In vitro experiments:MTS assay showed that sertraline did not cause significant cellular toxicity in TNF-a-induced BV2 cells at doses up to 2 ?M;Western blot results showed that TNF-a can activate microglia and highly express Iba-1 protein(P<0.001),sertraline could reduces the expression of Iba-1 in a dose-dependent manner(P<0.05,P<0.001),suggested that sertraline can inhibit TNF-a-induced microglial activation;Compared with the control group,the expression of inflammatory mediators TNF-a and iNOS in model group was significantly increased(P<0.001),sertraline could reduce the expression of these inflammatory mediators in a dose-dependent manner,suggested that sertraline can inhibit TNF-?-induced microglia inflammation;Western blot and immunofluorescence results showed that compared with the control group,the expression of pNF-KB in model group increased significantly(P<0.001)and a large amount of NF-?B was transferred to the nucleus,after the treatment of sertraline,the expression of pNF-?B significantly decreased(P<0.001)and the expression of NF-?B reduced in nucleus,suggested that sertraline can inhibit the activation of NF-?B in TNF-a-induced BV2 cells and inhibit the nuclear transfer of NF-?B by inhibiting the phosphorylation of I?B-?.Conclusion:Sertraline improves depression-like behavior in mice;Its mechanism may be related to blocking TNF-a/NF-KB signaling pathway in microglia and inhibiting the production of inflammatory mediators(TNF-?,IL-1?,iNOS(NO)).