Study On The Effect Of Surperfine Oat Bran On Intestinal Microflora And Lipid Metabolism In Obese Mice Induced By High Fat Diet

The prevalence of obesity and the prevalence of obesity-related diseases are currently increasing worldwide.A large number of studies have shown that gut microbes play a key role in obesity and its related diseases by influencing fat and glucose metabolism.Altering the diet structure and increasing the intake of dietary fiber are important ways to regulate intestinal microbes.Oat bran,as the main by-product of oat processing,contains plenty of dietary fiber and phenolic substances,which have the effect of regulating intestinal microbes,but it has not been fully utilized due to its rough taste.The superfine grinding technology can promote the release of nutrients in raw materials and improve their surface properties.It is still unclear about the mechanism of oat bran to regulate obesity and lipid metabolism.Therefore,the inhibitory effect of oat bran on digestive enzymes was studied by in vitro simulated digestion test with oat bran ultrafine powder.The effects of oat bran ultrafine powder on intestinal microbiota and short-chain fatty acids in normal and obese subjects were studied by simulated in vitro digestion and fermentation experiments and animal experiments.At the same time,untargeted metabolomics was used to study the effects of oat bran ultrafine powder on metabolites in high-fat diet-induced obese mice.To investigate the effect of oat bran ultrafine powder on lipid metabolism in obese mice induced by high fat diet in vitro and in vivo.The specific conclusions are as follows:(1)The superfine grinding could significantly reduce the particle size of oat bran and improve the water holding capacity,swelling capacity,water solubility,sodium cholate adsorption capacity and antioxidant properties of oat bran(P < 0.05).The highest contents of β-glucan and total phenol in oat bran were found at 5 min of superfine grinding treatment,reaching 11.59 g/100 g and 579.85 mg/100 g,respectively.Combining with the results of principal component analysis,the optimal grinding time for oat bran was 5 min.(2)The content of functional components such as β-glucan,polyphenols and flavonoids increased significantly(P < 0.05)after in vitro simulated digestion of oat bran.The inhibition of α-amylase,α-glucosidase,pancreatic lipase and cholesterol esterase increased significantly(P < 0.05)with increasing mass fraction of oat bran digest,and the inhibition rate and antioxidant properties of 5% oat bran digest for all four digestive enzymes exceeded 50%.(3)The results of simulated digestion and fermentation in vitro showed that oat bran superfine powder could significantly reduce the p H value of intestinal environment.Theα-diversity of intestinal microbiota in normal population was lower than that in obese population,and the microbial composition at 24 h and 48 h of fermentation was significantly different.At the phylum level,the intestinal microbiota composition of these two populations is the same.The abundance of Proteobacteria is the largest in the normal population,while the abundance of Firmicutes is the largest in the obese population.The addition of 5% oat bran has the most obvious effect on the regulation of intestinal microorganisms and the improvement of intestinal environment.It can significantly regulate the α-diversity and β-diversity of intestinal microorganisms,and promote the abundance of beneficial bacteria,such as Lactobacillus and Blautia.These results indicated that oat bran was helpful to regulate the composition of intestinal microbiota.(4)To study the effect of oat bran on lipid metabolism and intestinal microbial composition in obese mice by establishing a high-fat diet-induced obesity mouse model.The results showed that oat bran ultramicron powder significantly reduced the increase of body weight and abdominal fat caused by high-fat diet,decreased fasting blood glucose,significantly reduced serum levels of TC,TG,LDL-C,AST and ALT,and decreased Leptin content in liver and fat(P < 0.05).HE staining and section results showed that oat bran could significantly reduce the number of fat vacuoles in liver and small intestine,and the volume of abdominal adipocytes was also significantly smaller.The results of 16 S r RNA high-throughput sequencing showed that oat bran powder increased the abundance of Firmicutes,Lactobacillus,Bifidobacterium and Akkermansia and decreased the abundance of Bacteroidetes and Proteobacteria.(5)To establish a high-fat diet-induced obesity mouse model and study the effects of oat bran superfine powder on metabolites in high-fat diet-induced obesity mice by untargeted metabolomics.The results showed that oat bran could significantly improve the metabolic abnormalities caused by high fat diet,and six significantly different metabolites were screened out: C16 sphinganine,Delta2-THA,2-arachidonic glycerol,12-ketostonecholic acid,7-ketostonecholic acid,prostaglandin E2,which may be potential biomarkers for regulating obesity.And these were enriched to six lipid metabolism-related pathways,such as Linoleic acid metabolism,Sphingolipid signal metabolism,Prodigiosin biosynthesis.(7)The effect of oat bran superfine powder on the activity of lipid metabolism enzymes in AMPK signaling pathway in high-fat diet-induced obesity mice was studied.The results showed that oat bran increased the activities of AMPK and LPL,and then decreased the activities of ACC1,FAS and SREBPs in the liver of mice.Spearman correlation results showed that lipid metabolism-related enzymes(AMPK,FAS,ACC1,SREBPs and LPL),intestinal microorganisms(Bifidobacterium,Lactobacillus,Blautia)and differential metabolites(C16 Sphinganine,L-Isoleucine,12-ketolithocholic acid)were significantly correlated with each other.