Study On Functional Evaluation And Mechanism Of Alleviating Capsaicin Injury And Inhibiting Lipid Accumulation By Lactobacillus Plantarum S58 And Hull-less Barley β-glucan Synergistically

Hull-less barley is a kind of pure natural green food with comprehensive nutrition and convenient consumption,which is rich in protein,fiber and vitamins,and low in fat and sugar.Hull-less barley is the major food crop in the Qinghai-Tibet Plateau.β-glucan is the main active ingredient of Hull-less barley.In this study,a lactic acid strain capable of efficiently metabolizing hull-less barley β-glucan(β-G)was screened in vitro and the characteristics of β-G in vitro fermentation were explored.In addition,animal model experiments were used to evaluate the effects and the mechanisms of the target strain and β-G synergistically on the attenuation of peptic ulcer and obesity.The main results of this study are as follows:(1)A strain Lactobacillus plantarum S58(LP.S58)with the best metabolic ability toβ-G was screened by in vitro metabolism β-G experiments.Therefore,LP.S58 was used as the target strain for subsequent research to further explore its probiotic function.Fresh human feces were used to ferment β-G in vitro and the characteristics of β-G hydrolysis was studied.The experimental results showed that the p H value of β-G fermentation solution was significantly reduced after 48 hours of fermentation,and the contents of short-chain fatty acids in the fermentation significantly increased.At the same time,β-G increased the abundance of Bacteroides and decreased the abundance of Firmicutes.Furthermore,β-G also promoted the growth of beneficial bacteria such as Roseburia,Faecalibacterium,Bacteroides,and Bifidobacterium.(2)A capsaicin-induced gastrointestinal injury in mice was established to investigate the alleviation effect of LP.S58 and β-G synergistically on gastrointestinal injury.LP.S58 and β-G significantly increased capsaicin-induced weight loss in mice and significantly reduced gastrointestinal weight,alleviated gastrointestinal tract damage and pathological changes in gastrointestinal tissue of mice;LP.S58 cooperated with β-G to repaire the gastrointestinal mucosa of mice consuming capsaicin by inhibiting MTL,SP and promoting the secretion of gastrointestinal hormones such as SS,upregulating the expressions of EGF,EGFR,VEGF mRNA and protein in the stomach,and upregulating the expression of ZO-1 mRNA and protein in the duodenum;LP.S58 andβ-G synergistically reduced the levels of pro-inflammatory factors such as serum LPS,MPO,ICAM-1,IL-1β,TNF-α,IFN-γ,and regulated the NF-κB,TNF-α,IL-1β,IκB-αmRNA or protein expressions to inhibit inflammation;LP.S58 and β-G synergistically improved the intestinal flora of capsaicin gavage mice by reducing the relative abundance of Proteobacteria and reducing the relative abundance of Lachnospiraceae＿NK4A136＿group,unclassified＿Ruminococaceae,thereby inhibiting inflammation and improving gastrointestinal mucosa in mice.Eventually,the gastrointestinal damage caused by capsaicin gavage is attenuated.The results showed that LP.S58 cooperated with β-G to repair the gastrointestinal mucosa and inhibit inflammation by regulating intestinal flora to alleviate capsaicin-induced digestive tract injury.(3)A high fat diet(HFD)-induced obesity in mice was constructed to investigate the effect and the mechanism of LP.S58 and β-G synergistically on lipid accumulation.The experimental results showed that LP.S58 and β-G significantly reduced the body weight,lipid accumulation,and inhibited liver steatosis in HFD-fed mice,and reduced the serum levels of TC,TG,LDL-C,ALT,AST,and AKP and increased HDL-C level.LP.S58 and β-G synergistically reduced serum LEP levels,thereby weakening leptin resistance.In liver and adipose tissues,LP.S58 and β-G synergistically reduced the mRNA expressions of PPAR-γ,C/EBPα,SREBP-1c,FAS,SCD1,LPL and up-regulated the protein expression of p AMPK while down-regulated the protein expressions of PPAR-γ and C/EBPα by activating the AMPK metabolic pathway to decrease lipid synthesis and fatty acid uptake,furthermore,the mRNA expressions of CPT-1 and HSL significantly up-regulated to increased lipolysis and lipid oxidation.After LP.S58 and β-G synergistically treatment,the HFD-induced decreases in GLP-1,PYY,and ADP were markedly reversed and the expressions of colonic ZO-1,occludin,and claudin-7 were increased to suppress systematic and colonic inflammation,while activating the AMPK signaling pathway.LP.S58 and β-G ameliorated gut microbiological dysbiosis in HFD-fed mice by increasing the abundance of Lactobacillus,Akkermansia,Faecalibaculum,Dubosiella,Allobaculum,and Turicibacter and reducing the abundance of Ruminococcaceae-UCG-014,Helicobacter,and Bacteroides.Spearman’s rho non-parametric correlation analysis showed that there was a significant correlations between obesity-related indicators and certain species in the intestine.The above results showed that a synbiotics composed of LP.S58 and β-G inhibited lipid accumulation in mice.LP.S58 in cooperation with β-G inhibited inflammation and promotes intestinal hormones such as GLP-1,PYY by regulating the intestinal flora,thereby activating the AMPK signaling pathway.The activation of AMPK signaling to reduce lipid accumulation by accelerating lipolysis and fatty acid oxidation and inhibiting fatty acid uptake and lipid synthesis.