Study On The Relationship Betweem Gut Microbiota And Expression Of Key Enzymes In Long Chain Fatty Acid Metabolism

With the improvement of people's living standard,people's demand for health is higher and higher.Many diseases are caused by bad eating habits and little exercise.A very important part is obesity,diabetes,hypertension and other diseases caused by disorders of lipid metabolism.Gut microbiota is closely related to the human health and had a significant effect on lipid metabolism.Intestinal microflora interact with the host to regulate the body's lipid metabolism.But it is not clear which bacteria plays a decisive role in the pathogenesis of obesity and metabolic diseases.In-depth study can provide new targets for the prevention and treatment of diseases caused by these disorders of lipid metabolism from the perspective of gut microbiota.Dietary fatty acid metabolism is an important part of lipid metabolism,which closely relates to metabolic diseases and nutrition.Metabolic pathways include: Transport of long-chain free fatty acids into small intestinal cells.Synthesis and secretion of chylous particles in intestinal cells.Degradation of chylous particles.The key enzymes include:(1)Fatty acid transporter 4(FATP4)and fatty acid binding protein 4(FABP4)were involved in the transport of long chain fatty acid membranes.(2)Monoacylglycerol acyltransferase 2(MGAT2)and diacylglycerol acyltransferase 1(DGAT1)were involved in the synthesis and secretion of chylic particles.(3)Lipoprotein lipase(LPL)required for chlor microparticle degradation.At present,there is little research on the relationship between gut microbiota and the expression of key enzymes in fatty acid metabolism.Therefore,the correlation between gut microbota and the expression of key enzymes in long chain fatty acid metabolism was studied.1)The effects and mechanism of Short chain fatty acids(SCFA)on the differentiation of 3T3-L1 cells were studied.SCFA such as acetic acid,propionic acid and butyric acid were produced by fermentation processes of gut microbiota.The effects of SCFA on the viability of 3T3-L1 cells was investigated by MTT assay.MTT results showed safe concentrations of acetic acid,propionic acid and butyric acid were 0-6.4 mM,0-3.2 mM and 0-0.8 mM,respectively.Oil Red O staining was used to visualize lipid content in 3T3-L1 cells.Triglyceride assay kit was used to quantitative detected triglyceride content.And the results showed treatment with acetic acid,propionic acid and butyric acid accelerated the 3T3-L1 adipocyte differentiation;qRT-PCR and western blot were used to evaluate expression of metabolic enzymes.The results showed expression of fatty acid synthetase(FAS),LPL,FABP4 and FATP4 were significantly improved by the SCFA treatment(P<0.05).Therefore,SCFA had a significant effect on the expression of key enzymes in fatty acid metabolism in adipocytes,and promoted the lipid accumulation by modulating the expression of enzymes of fatty acid metabolism.2)By using ceftriaxone sodium to induce intestinal dysbacteria in mice,the effects of antibiotics on the composition of gut microbota and the expression of enzymes of long chain fatty acid metabolism in mice were studied.The structural changes of dominant bacteria in mice were analyzed by high-through sequencing.The most changes in intestinal microbiota communities were Firmicutes and Bacteroidetes,from which following increased abundance(Clostridia and Clostridiales)and decreased abundance(Bacteroidia,Bacteroidales,Bacteroidaceae,Bacteroide),and caused a decrease of the contents of SCFA,but an increase of Lipopolysaccharide(LPS).The mRNA expression of enzymes of long chain fatty acid metabolism was analyzed by qRT-PCR.The qRT-PCR results showed that the expression of FATP4,LPL and FABP4 were significantly up-regulated,while DGAT1 and MGAT2 were down-regulated with antibiotics treatment.These data indicated the imbalance of mice caused by antibiotics,accompanied by the abnormal expression of key enzymes in long chain fatty acid metabolism.3)Based on the imbalance of gut microbiota induced by high-fat diet in mice,the effects of high-fat diet on the composition of intestinal flora and the expression of enzymes of long chain fatty acid metabolism in mice were studied.The influence of high-fat diet on the intestines of mice was examined by high-through sequencing.High-fat diet caused the increase of Bacteroidetes(Bacteroidia,Bacteroidales,Bacteroidaceae,Bacteroide)and the decrease of Firmicutes(Clostridia,Clostridiales,Lachnospiraceae,Clostridium XlVa)in the feces of mice,following a decrease the content of acetic acid and an increase of LPS.The mRNA expression of enzymes of long chain fatty acid metabolism was analyzed by qRT-PCR.The qRT-PCR results showed that the expression of FATP4,LPL,DGAT1,MGAT2 and FABP4 were significantly up-regulated.These data indicated high-fat diet caused dysfunctional flora,and the fatty acid metabolism disorder caused by high-fat diet was related to the significant increase of FABP4,LPL,FATP4,DGAT1 and MGAT2 mRNA expression.4)Integrate antibiotic treatment with high-fat diet models,we found Acetatifactor and Escherichia/Shigella had significant correlation with the FATP4,LPL and FABP4 in mice using IBM SPSS Statistics 22 correlation analysis(P<0.05).