The Effect And Mechanism Of Ellagic Acid On The Improvement Of Depression-like Behavior In Chronic Stress Model Mice

Ellagic acid(EA)is a rich source of polyphenol dilactone with significant anti-inflammatory and neuroimmune activity.In this paper,the antidepressant effect of ellagic acid was evaluated in chronic unpredictable mild stress model(CUMS)mice.Sucrose preference(SPT),tail suspension test(TST)and forced swimming test(FST)were used to evaluate the effect of EA on depression-like behavior in CUMS model mice;UPLC-TOF-MS was used to analyze the effect of EA on serum metabolites in CUMS mice;Metagenome analysis of EA on the structure and function of intestinal microflora in CUMS depression mice.The main findings are as follows:1.The effect of EA on the behavior of CUMS-induced miceAfter CUMS stimulation and EA intervention for 6 weeks,sucrose preference test(SPT),tail suspension test(TST)and forced swimming test(FST)were used to evaluate the antidepressant effect of EA on CUMS-induced mice.The weights of control group,model group,EA-100 group(100 mg/kg EA,gv)and EA-20 group(20 mg/kg EA,gv)were 25.61 ± 1.79 g,21.91 ± 2.21 g,23.08 ± 2.33 g and 24.04 ± 1.74 g,CUMS stimulation caused significant weight loss in experimental animals,and EA intervention can significantly alleviate CUMS-induced weight loss.Compared with the model group,the sucrose preference rates of the EA-100 and EA-20 groups increased by 27.66%(p?0.05)and 28.24%(p?0.05),respectively.The immobility time of TST decreased by 31.41%(p?0.01)and 27.68%(p?0.05),respectively.The immobility time of FST was reduced by 46.20%(p ? 0.05)and 24.41%(p ? 0.05),respectively.The results show that EA intervention can significantly improve CUMS-induced depression-like behavior.2.Effect of EA on biomarkers of CUMS-induced miceCompared with the CUMS model group,the BDNF content in the hippocampus and prefrontal cortex of the EA-100 group increased by 45.02%(p?0.05)and 50.90%(p?0.05),20.68%(p ? 0.05).At the same time,EA intervention significantly improved CUMS-induced serum levels of inflammatory factors in mice.Compared with the model group,the levels of TNF-? and IL-1? in the serum of mice in the EA-100 and EA-20 groups were reduced by 54.74%(p < 0.01),45.48%(p < 0.01)and 29.82%(p < 0.01),13.08%;serum IL-10 levels in mice increased by 205.96%(p < 0.01)and 180.59%(p <0.01),respectively.The results show that ellagic acid can increase BDNF,5-HT,IL-10 and decrease the levels of TNF-? and IL-1? to improve the neuroendocrine and inflammatory response of model mice,and play an antidepressant effect.3.Effect of EA on serum metabolites of CUMS depression model miceThe results of mass spectrometry data analysis of serum metabolites in experimental mice showed that there were 20 main metabolites with significant differences between the model group and the control group,16 were significantly up-regulated,and 4 were significantly down-regulated.There were 20 significantly different metabolites in the EA-100 group and the model group,15 species were significantly reduced,and 5 species were significantly increased.100 mg/kg ellagic acid intervention improved 75% of metabolites induced by CUMS,including 4-imidazolone-5-propionic acid,isoglutamine,5phosphatidylethanolamines(PE),4 Kinds of phosphatidylinositol(PI)and uric acid were significantly down-regulated,and N-stearoylserine,N-acetyl-DL-serine and PE and 1 PE were significantly up-regulated.Metabolic pathway analysis showed that CUMS-induced depression mice are deregulated in the four pathways of histidine metabolism,sphingolipid metabolism,glycerophospholipid metabolism,arginine and proline metabolism.EA may play a role by improving the amino acid metabolism and lipid metabolism pathways of CUMS mice Antidepressant effect.4.Effect of EA on the structural composition of intestinal flora of CUMS-induced miceMetagenome sequencing results showed that CUMS-induced depression-like behavior caused changes in the composition of the intestinal flora of mice at various classification levels.Compared with the control group,the relative abundance of Lactobacillus,Faecalibaculum,Bacteroides and Prevotella in the model group was significantly reduced,the Clostridium was significantly increased.The intervention of ellagic acid increased the abundance level of Bacteroides(p ? 0.05),Prevotella(p ? 0.05)and decreased the Lactobacillus(p?0.05)and decrease the Lactobacillus(p?0.01)and Clostridium(p?0.05)relative abundance level..At the species level,Prevotella sp.CAG: 485,Bacteroides sp.CAG: 927 and Bacteroidales bacterium 52?46 are the main dominant strains of the ellagic acid group.It is speculated that they may be the key strains of anti-depressant-like behavior of ellagic acid and participate in the intestinal metabolism of ellagic acid.5.Effect of EA on the function of intestinal microflora in CUMS-induced miceMetagenomic sequencing KEGG function prediction results show that KEGG level 1is mainly concentrated in the metabolic pathway,mainly including amino acid metabolism,nucleotide metabolism and metabolism of cofactors and vitaminsetc.At the level of KO,210 KO pathways in the ellagic acid group and model group were significantly changed,including Glycine,serine and threonine metabolism(p < 0.001);TCA cycle(p < 0.001);Folate biosynthesis(p < 0.001);Drug metabolism-other enzymes(p < 0.001);Vitamin B6metabolism(p < 0.001)and other pathways increased significantly,and the Nucleotide excision repair pathway decreased significantly(p < 0.01).This indicates that the CUMS caused significant changes in the function of intestinal flora in mice,and ellagic acid can partially improve the disturbance of these intestinal flora.