The Mechanism Of Simo Decotion In LPS Depression Model Mice Based On Gut-Brain Axis

ObjectivesThis article takes "gut-brain axis" as the basis point to explore the potential mechanism of action of Simo decoction on Lipopolysaccharide(LPS)-induced acute depression in mice,and how Simo decoction intervenes in depression through "gut-brain axis",so as to provide a new way to play its antidepressant effect.MethodsSixty C57BL/6 male mice were randomly divided into 6 groups,including blank group,model group,positive drug group,low dose,medium dose,and high dose of Simo decoction,with 10 mice in each group.In the positive drug group,20 mg / kg fluoxetine(dissolved in distilled water),the low,medium and high dose groups of Simo decoction respectively(all dissolved in 0.5% CMC solution),and the blank group and model group received equal distilled water(0.1 m L/10 g,i.g.)for 7 consecutive days.After 90 minutes of the last intragastric administration,mice in the model group,the positive drug group,and the Simo decoction group were intraperitoneally injected with LPS(0.83 mg/kg,i.p.),while mice in the blank group were intraperitoneally injected with an equal amount of physiological saline for two consecutive days to establish an acute depression model.On the second day,after injecting LPS 24 hours,sugar preference,tail suspension,and forced swimming experiments were conducted on mice.The success of modeling was tested by comparing the differences in sugar preference rate,tail suspension,and swimming immobility time between the model group and the blank group mice.After the behavioral test,the contents of colon,cerebral cortex and cecum required for the later experiment were taken out and stored in the refrigerator at-80 °C for use.Western Blot method and quantitative reverse transcriptase polymerase chain reaction(RT-q PCR)were used to detect the expression of tight junction protein 1(ZO-1)and closure protein Occludin in mouse colon tissue,as well as the expression of ZO-1,Occludin,interleukin-1(IL-1 β)、 IL-6 and Tumor Necrosis Factor(TNF-α)Changes in m RNA expression levels;RT-q PCR assay was used to detect brain derived neurotrophic factor(Bndf),neurotrophic factor 3(Ntf3),complement component C1qlike2(C1ql2),IL-6,and IL-1β m RNA expression level in the cerebral cortex.Finally,16 S r RNA sequencing technology was used to detect the effect of Simo decoction on intestinal microflora by comparing species annotations,sample complexity analysis,and multi sample analysis among different groups.Results(1)Effect of Simo Decoction on LPS induced depressive behavior in mice.In the sugar water preference experiment,the sugar water preference value of the model group was significantly lower compared with the blank group(P <0.01).For 7 days,the low,medium and high dose values increased(P <0.05).In the suspended tail experiment,the time of inactivity(T)increased significantly compared with the blank group(P <0.005).Continuous 7 After gastric administration,mice T shortened with measurement-dependent T value(P <0.01).In the forced swimming experiment,the imswimming time time was significantly longer compared with the blank group(P <0.005).For 7 days,the positive drug and the low,medium and high dose groups were shortened(P <0.01).(2)The effect of simo decoction on intestinal barrier in depressed mice.Compared with the normal group,LPS induced a decrease in the protein expression of ZO-1 and Occludin in the colon tissue of mice in the model group.After 7 consecutive days of intragastric administration of Simo decoction,the protein expression of Occludin and ZO-1increased to varying degrees,and the effect of increasing the protein expression of Occludin and ZO-1 in the high-dose group of Simo decoction was more significant(p<0.05 or(P<0.01)).Further detection of intestinal inflammatory genes using RT-q PCR showed that the expression levels of ZO-1 and Occludin genes in the LPS-induced model group were extremely downregulated,while IL-1 β、 IL-6 and TNF-α Genes have a high upward trend.Both ZO-1 and Occludin in the Simo decoction treatment group showed an upward trend(p<0.001,p<0.0001),while IL-1 in the Simo decoction treatment group showed an upward trend β、 IL-6 and TNF-α The level decreased(p<0.0001),and the effect of the high dose group of Simo decoction was better.(3)Effect of Simo Decoction on Inflammatory Response of Cerebral Cortex in Depressed Mice.Compared with the normal group,the expression levels of Bndf,Ntf3,and C1ql2 in the model group were significantly decreased,and IL-6 and IL-1 were significantly decreased βThe expression level was significantly upregulated.Compared with the model group,Simo decoction can reduce the inflammatory factors IL-6 and IL-1 in the cerebral cortex of mice induced by lipopolysaccharide β(P<0.01 or p<0.001 or p<0.0001),and the expression of Bndf,Ntf3,and C1ql2 was significantly upregulated by Simo decoction(P<0.05 or P<0.01 or p<0.0001).(4)The effect of simo decoction on intestinal flora in depressed mice.The Shannon index represents the abundance and evenness of intestinal microflora.The Shannon index of fluoxetine group and Simo decoction group increased,but there was no significant difference,indicating that the bacterial diversity of Simo decoction group was increasing.According to the analysis of OTU(Operational Taxonomic Units),the abundance of OTUs in the Simo decoction group increased,indicating that Simo decoction can change the abundance of intestinal flora.Principal coordinate analysis(PCo A)based on Weighted Unifrac distance showed that the structure of intestinal microbiota in the Simo decoction group was separated from that in the control group,indicating that Simo decoction could change the structure of intestinal microbiota.Through the arithmetic mean unweighted pair method(UPGMA)analysis,there is a good difference between the Simo decoction treatment group and the blank group and the model group.It shows that Simo decoction has a strong regulatory effect on intestinal flora in mice.At the level of genus,compared with M,Simo Decoction could increase the relative abundance of Parabacteroides and reduced the relative abundance of Lactobacillus.Besides,in Low group,the relative abundance of Helicobacter,Candidatus＿Saccharimonas,Roseburia,Prevotellaceae＿UCG-001,Rikenellaceae＿RC9＿gut＿group,Muribaculum,GCA-900066575 increased significantly;in Middle group,the relative abundance of Alloprevotella,Prevotellaceae＿UCG-001 increased significantly,Enterorhabdus reduced;in High group,the relative abundance of Lachnospiraceae＿NK4A136＿group,Parasutterella,Odoribacter,Alloprevotella,Rikenellaceae＿RC9＿gut＿group,Muribaculum increased significantly,the relative abundance of Enterorhabdus reduced significantly.It is speculated that the change of relative abundance of these gut bacteria may have some effects on depression.Conclusion1.Different doses of Simo decoction have antidepressant effects,and the high dose group have the best effect.2.Simo decoction can alleviate the inflammatory depression-like symptoms induced by LPS through the "gut-brain axis".Its mechanism of action may be related to the regulation of intestinal flora,inhibiting pro-inflammatory cytokines,protecting the intestinal barrier,protecting neurons,and increasing the level of neural endogenous factors.