Effects Of Arabinoxylan Oligosaccharide Combined With Tea Polyphenols On Preventing Obesity And Regulating Gut Microbiota In Mice

Obesity and its complications have become a global public health problem.Changes in the structure and function of the gut microbiota can affect the host’s energy metabolism,insulin sensitivity,and gut barrier integrity,and play an important role in the occurrence and development of obesity and its complications.Dietary fiber and polyphenols in foods such as fruits,vegetables and whole grains have functional properties that modulate gut microbiota,reduce body weight,and improve metabolism.However,how dietary fiber and polyphenols work together on the gut microbiota and its effect on body weight is unclear.Arabinoxylan oligosaccharide(AXOS)extracted from rice bran has the effect of regulating gut microbiota and improving immune function,but its role in preventing obesity is still unclear.Green tea polyphenols(GTP),the main phenolic substances in green tea,also have the effect of regulating gut microbiota and improving body weight.However,the effect of GTP combined with AXOS on obesity prevention and the regulation of gut microbiota is still unclear.Therefore,this study uses AXOS and GTP as the representative of dietary fiber and polyphenols to study the effects of AXOS and GTP on glucose metabolism,lipid metabolism and gut microbiota.Thus,provide new ideas and theoretical basis for dietary fiber combined with polyphenols to prevent obesity.The main research contents and results are as follows:(1)The obesity mouse model was established by high-fat diet(HFD)to study the preventive effect and mechanism of AXOS on diet-induced obesity.The results showed that AXOS significantly reduced the body weight of mice,inhibited fat accumulation and hepatic steatosis,and improved glucose tolerance in mice.AXOS decreased serum total cholesterol(TC),total triglyceride(TG)and low-density lipoprotein cholesterol(LDL-c)levels,while increased high-density lipoprotein cholesterol(HDL-c)levels;inhibited the expression of fat synthesis-related genes,including down-regulated the expression levels of sterol regulatory element-binding protein(SREBP-1c),fatty acid synthase(Fasn),and peroxisome proliferator-activated receptor-γ(PPAR-γ),but upregulated the expression level of the fat oxidation gene peroxisome proliferatoractivated receptor-α(PPAR-α).AXOS also significantly decreased serum lipopolysaccharide(LPS)and inflammatory factors,including tumor necrosis factor-α(TNF-α)and interleukin-6(IL-6).In addition,AXOS promoted the production of shortchain fatty acids(SCFAs).AXOS increased the relative abundance of “antiinflammatory” bacteria,including Bifidobacterium and Akkermansia,and decreased the relative abundance of “pro-inflammatory” bacteria,including Anaerotruncus,Helicobacter,Coprococcus,and Desulfovibrio.The possible mechanism by which AXOS regulates lipid metabolism and improves obesity is to promote the growth of“anti-inflammatory” bacteria in the gut,inhibit the growth of “pro-inflammatory”bacteria,and reduce the production of LPS in serum,thereby improving systemic inflammation and obesity.(2)By comparing the effects of AXOS,GTP and AXOS combined with GTP(G+A)on the prevention of obesity in HFD-induced mice,explore the mechanism of AXOS combined with GTP to prevent obesity.By comparing body weight,fat distribution,blood lipid levels,and oral glucose tolerance,it was found that AXOS and G+A had significant fat-reducing effects,while GTP had no significant fat-reducing effects.The fat-reducing effect of G+A was not significantly different from that of AXOS,but it had a significant improving effect on glucose tolerance in mice.This may be related to the different mechanisms by which GTP and AXOS regulate the expression levels of lipid metabolism-related genes.AXOS,GTP and G+A all inhibited the expression of fat synthesis-related genes including SREBP-1c,Fasn,and PPAR-γ,and there was no significant difference among the three groups.However,in the expression of fat oxidation genes,GTP promoted the expression of carnitine palmitoyltransferase-1α(CPT-1α)in the liver,AXOS promoted the expression of CPT-1α in epididymal adipose tissue,but G+A has no promoting effect,which may be related to the different mechanisms of GTP and AXOS affecting CPT-1α in different organs.In the three groups,AXOS and G+A up-regulated the expression level of lipid oxidation-related gene(PPAR-α)in fat,indicating that GTP had no significant effect on PPAR-α expression.(3)Illumina high-throughput sequencing technology was used to explore the effect of AXOS combined with GTP on gut microbiota.Biodiversity in feces was analyzed,and it was found that AXOS significantly reduced the diversity of gut microbiota,while G+A maintained a high diversity of gut microbiota.Through the relative abundance of species and the principal coordinate analysis based on Uni Frac distance,it was found that both AXOS and G+A could significantly affect the structure of gut microbiota.AXOS promoted the growth of bacteria such as Bifidobacterium and Akkermansia,while reduced the relative abundance of Lactobacillus,but G+A had less effect on Bifidobacterium and did not reduce the relative abundance of Lactobacillus.This is related to the effect of GTP on the regulation of AXOS on the microbiota in the gut.Analysis of SCFAs levels showed that AXOS significantly increased the content of total SCFAs,acetate,and butyrate in feces,similar to the G+A group.This suggests that although GTP affects the microbiota regulation of AXOS,it does not alter the SCFAs-producing capacity of the gut microbiota.In addition,through the correlation analysis of gut microbiota and obesity-related indicators,Bifidobacterium,Akkermansia,and Alistipes were found to be associated with the production of SCFAs and the improvement of obesity-related indicators.Taken together,rice bran derived AXOS significantly prevents high-fat dietinduced obesity in mice by modulating gut microbiota and SCFAs.GTP did not significantly increase the fat-reducing effect of AXOS,but significantly improved the effect of AXOS on the diversity of intestinal flora.This is related to the fact that GTP affects the regulation of microbiota structure by AXOS,but does not affect the production of SCFAs by AXOS in the gut.