Study On The Effect And Mechanism Of Sertraline On Toxoplasma Gondii Infection Induced Mice Depression-like Behaviors

Objective:In this study,female BALB/c mice and the mouse microglia cell line(BV2)cells were used as research objects.A mouse model of acute Toxoplasma gondii(T.gondii)infection and a BV2 cell activation model were established by infecting tachyzoites of the T.gondii RH strain to explore the effect and mechanism of sertraline(SERT)on T.gondii and T.gondii-induced depression-like behaviors in the host,thereby providing new theoretical and experimental evidence for drug to prevent and cure toxoplasmosis.Methods:(1)In vivo experiments:female BALB/c mice were randomly divided into normal group(N,uninfected+untreated),model group(CN,T.gondii-infected and untreated),SERT group(T.gondii-infected and treated with 10 mg/kg SERT)and positive control group(sulfadiazine sodium(SD-Na),T.gondii-infected and treated with 100 mg/kg SD-Na).Except for the mice in the N group,each mouse was intraperitoneally injected with 1 X 105 T.gondii RH tachyzoites to establish an acute T.gondii infection mouse model.After 4 h of infection,the mice were orally administered with ultrapure water,10 mg/kg SERT or 100 mg/kg SD-Na once a day for 6 days.Subsequently,the effects of SERT on T.gondii infection host were investigated by observing and recording the survival of the mice within 10 days.On the sixth day after infection,the effects of SERT on depression-like behaviors induced by acute T.gondii infection were observed through forced swimming test,tail suspension test and sucrose preference test,and the in vivo anti-T.gondii effect of SERT was further explored by RH counting and Western blot experiments.(2)In vitro experiments:The MTS method was used to detect the effect of SERT on the proliferation of BV2 cells.In addition,the cells were infected with T.gondii for 4 hours at a ratio of T.gondii:cell=5:1.After the free T gondii was washed away,the cells were incubated with different drug solutions for 36 h.Then,trypan blue counting,immunofluorescence,RT-PCR and Western blot experiments were used to investigate the anti-T.gondii effect of SERT in vitro.(3)Mechanism study:Western blot was used to detect the effect of SERT on the expression of Iba-1,iNOS,TNF-α,IFN-γ,TLR4,TRIF,p-NF-κB p65,p-IκBα,NF-κB p65 and IκBα proteins in BV2 cells and mouse brain tissues.The effect of SERT on the expression of Iba-1 and nuclear translocation of NF-κB p65 in BV2 cells was detected by immunofluorescence.In addition,the effects of SERT on the levels of TNF-α,IFN-y,5-HT,DA in serum and IDO,5-HT,DA in brain tissues were studied using ELISA technology.Results:(1)In vivo experiments:SERT significantly prolong the survival time of mice infected with T.gondii,improve the depression-like behavior of mice induced by acute T.gondii infection,and reduce the expression of SAGI protein in the brain tissue of mice and the number of T.gondii in mice peritoneal contents.(2)In vitro experiments:When the SERT concentration is less than or equal to 2 ptM,it is not toxic to BV2 cells.In addition,SERT significantly improve the survival rate of T.gondii infected BV2 cells,and reduce the expression level of tachyzoite-specific SAG1 and T.g.HSP70 mRNA in the cells.(3)Mechanism study:SERT significantly inhibited the expression of Iba-1,TNF-α,IFN-y and iNOS in T.gondii infected BV2 cells and mouse brain tissues,and reduced the levels of TNF-α and IFN-y in mouse serum.At the same time,SERT reduced the expression of TLR4 and TRIF proteins in T.gondii infected BV2 cells and mouse brain tissues,and inhibited IκBαphosphorylation and NF-κB p65 nuclear translocation induced by T.gondii infection.In addition,SERT can significantly reduced the level of IDO in the brain tissue of mice infected with T.gondii,and increased the levels of 5-HT and DA in the brain tissue and serum of mice.Conclusion:SERT has a good anti-T.gondii effect,and effectively inhibits the inflammation response and neurotransmitter metabolism disorders induced by T.gondii infection through down-regulating the TLR4/NF-κB signaling pathway,thereby improving depression-like behaviors in mice infected with T.gondii.