Preliminary Study On Antidepressant Effect Of Bifidobacterium W112

Depression is a common psychiatric disorder.Many studies have shown that probiotics can regulate the microbiome-gut-brain axis and play an important role in the treatment of depression.Bifidobacteria are a beneficial bacteria in the intestinal tract of the body.Therefore,we will conduct a preliminary study on the mechanism of Bifidobacterium W112 to improve the behavior of depressed mice,and obtain the following results.1.To evaluate the antidepressant effect of Bifidobacterium W112 by behavioral experiments.The results showed that Bifidobacterium W112 increased the motor activity of the depressed mice in the open field test(p<0.05),decreased the immobility time in forced swimming test(p<0.05),and increased the sucrose preference in the sucrose preference test(p<0.05).It showed that Bifidobacterium W112 had an antidepressant effect.2.The concentration of Trp(Tryptophan),5-HT(5-hydroxytryptamine),5-HIAA(5-hydroxyindoleacetic acid)in the hypothalamus,and the concentrations of Trp,KYN(Kynurenine),KYNA(Kynurenic Acid)serum were determined to evaluate tryptophan metabolism pathway.The concentration of CRH(corticotropin releasing hormone)in hypothalamic,and the concentration of CORT(corticosterone),ACTH(corticotropin)in serum were deternined to assess function of HPA Axis.The results showed that Bifidobacterium W112 increased content of 5-HT,decreased Trp/KYN(p<0.05),and increased content of KYNA(p<0.05),which improved the damage of tryptophan metabolism pathway.At the same time,Bifidobacterium W112 decreased content of CRH(p<0.05),suggusting that it reversed the hyperactivity of the HPA axis.It indicated that Bifidobacterium W112 improved the changes of depression-associated biomarkers.3.The degree of liver damage was assessed by measuring the ratio of ALT(alanine aminotransferase)to AST(aspartate aminotransferase)in serum.The gene expression associated with liver metabolism was measured by RT-qPCR to explore the mitigation mechanism of liver damage.The results showed that Bifidobacterium W112 decreased the AST/ALT ratio of depressed mice(p<0.05),indicating that liver damage was alleviated.In the phospholipid metabolism,the expression of Pla2g15(lysophospholipase I)was decreased(p<0.05).In the bile acid metabolism,the expression of gadl(glutamate dehydrogenase)was decreased(p<0.05).In hepatocyte apoptosis,the Bel-2/Bax ratio was increased(p<0.05).The results indicated that Bifidobacterium W112 regulated hepatic metabolic disorders by inhibiting hepatocyte apoptosis and interfering with phospholipid and bile acid metabolism.4.The effects of Bifidobacterium W112 on colon morphology and intestinal flora were analyzed by colon tissue sections and 16S diversity sequencing technology.The results showed that Bifidobacterium W112 restored the length of small intestine villi in depressed mice,and relieved the damage of intestinal physiological barrier.Bifidobacterium W112 increased the relative abundance of beneficial bacteria Bifidobacterium,Lactobacillus,Akkermansia,and reduced the relative abundance of harmful bacteria Clostridium.It relieved the damage of the intestinal biological barrier and explained the reason of Bifidobacterium W112 relieving liver injury from the perspective of intestinal flora.Bifidobacterium W112 increased the alpha diversity of the intestinal flora and increased the ability of the intestinal tract to resist stress.PICRUSt identified abundance changes of genes associated with intestinal tryptophan metabolism that could connect with the changes of the host's tryptophan metabolism.In conclusion,Bifidobacterium W112 could regulate 5-HT system,tryptophan ruetabolism,HPA axis function and depression-related liver damage to alleviate depressive-like behavior by interferring with intestinal microorganisms.The ideal properties of this strain could make them potential probiotics for the prevention or treatment of depression.