Study On The Regulation Of Fucha Water Extract On Intestinal Microecology And Body Metabolism In High-fat-induced Obese Mice

Fu brick tea(FBT)is a black tea,and many studies report that Fu brick tea has obvious obesity-inhibiting effects,which may work by regulating the gut microbiota.At present,studies relating to intestinal microbiota of obese mice regulated by FBT mainly focused on taxonomy level,but the possible target microbes and its function are still unclear.Moreover,little is known whether FBT improve obese condition mainly by affecting intestinal microecology and thereby changing general metabolism.In addition,FBT is rich in bioactive substances with small molecules,which may be absorbed into blood stream in the digestive tract and act directly on target organs.Therefore,this study used obese mouse model,pseudo sterile mouse model and fecal bacteria transplantation(FMT)to analyze the differences between intestinal microecology and serum metabolites,aiming to explore the mechanism of Fu brick tea extracts(FTEs)in regulating lipid metabolism and deposition in high fat diet(HFD)induce obesity.The main contents of this study are as follows:First effect of FTEs on lipid deposition and intestinal microorganisms in obese mice induced by HFD(experiment 1).Forty C57BL/6 male mice were randomly divided into five groups:control group(Chow),the high-fat diet group(HFD),the FTEs treatment group(FTEs),the antibiotic treatment group(Anti)and the antibiotic and FTEs treatment group(Anti+FTEs),and the study lasted for consecutive 8 weeks.Compared with the HFD group,FTEs significantly reduced the body weight(p<0.01),liver weight(p<0.001)and fat mass(epididymal fat:p<0.05,subcutaneous fat:p<0.001,mesenteric fat:p<0.001,and retroperitoneal fat:p<0.01),levels of serum total cholesterol(TC,p=0.073),liver aspartate aminotransferase(AST,p<0.01)and glucose tolerance(p<0.05).In addtion,the results of 16S rRNA high-throughput sequencing showed that FTEs significantly increased the diversity of intestinal microbiota and the relative abundance of short-chain fatty acids(SCFAs),including Akkermansia,Bacteroides,P arabacteroide s,Alistipes,Lachnospiraceae_NK4A136_group(p<0.05)when compared with the HFD group.Moreover,in pseudo germ-free mice,compared with the single feeding HFD group,FTEs still can significantly reduce the body weight(p<0.001),fat mass(epididymal fat:p<0.001,subcutaneous fat:p<0.001,mesenteric fat:p<0.001,retroperitoneal fat:p<0.001),serum TC(p<0.001),LDL-C(p<0.01).Most of the gut microbiota of mice were eliminated by antibiotic coctail except for Parabacteroides and Bacteroides at genus level.Furthermore,LEfSe analysis showed that FTEs could significantly increase the relative abundance of Bacteroides.The results suggest that FTEs can change the intestinal microecological composition of mice,Parabacteroides and Bacteroides may play an important role in the intervention of HFD-induced obesity,and the genera of Bacteroides uniformis may be the target microorganisms.Secondly,the effects of intestinal microorganisms on HFD induced obesity were investigated by fecal microbiota transplantation(FMT).Feces from Chow,HFD and FTEs groups in experiment 1 were collected from the fourth week,and then were transplanted to three groups of C57BL/6 male mice(n=8)feeding with HFD(FMT-Chow,FMT-HFD,and FMT-FTEs),and the experiment lasted for consecutive 8 weeks.Compared with the FMT-HFD group,FMT-FTEs could significantly reduce the body weight(p<0.01),fat deposition(epididymal fat:p<0.05,subcutaneous fat:p<0.01,retroperitoneal fat:p<0.05,mesenteric fat:p<0.05)and serum TC content(p<0.001).FMT-FTEs could significantly reduce the relative abundance of Staphylococcus(p<0.01),but the relative abundance of Alistipes,Bacteroides and Parabacteroides in Bacteroidetes showed increasing trend(p>0.05).The results suggested that gut microorganisms played important roles involved the lipid-lowering effect of FTEs.In addition,there were no significant differences in lipid deposition and metabolism between FMT-Chow and FMT-FTEs groups,suggesting that the interference of FTEs on HFD induced obesity might work through some other ways besides intestinal mieroorganisms,and possible mechanism needs further research.Thirdly,the effect of FTEs on serum metabolites of obese mice induced by high fat diet.The sera of mice from Chow,HFD and FTEs group was collected after 8 weeks of treatment in an experimental animal(n=6)for UHPLC-QE-MS non-target metabolome analysis.A total of 392 metabolites were detected in this study.It was found that there were 21 differentially abundant metabolites between Chow and HFD groups(VIP>1 and p<0.05),and 9 differentially abundant metabolites between HFD and FTEs groups(VIP>1 and p<0.05).Furthermore,KEGG was used for functional enrichment of those metabolites.Compared with Chow group,the HFD mainly affected the synthesis and metabolism of amino acids,while FTEs mainly affected caffeine metabolism in mice.In addition,correlation analysis of differential metabolites and differential genera of microbes showed that the FTEs enriched Lachnospiraceae_NK4A136_group and norank_f_lachnospiraceae were positively correlated to caffeine(p<0.05,r=0.70;p<0.01,r=0.83),theophylline(p<0.05,r=0.73;p<0.01,r=0.82).Simultaneously,norank_f_Lachnospiraceae were positively correlated to theobromine(p<0.01,r=0.68;p<0.01,r=0.86).The results suggest that FBT may regulate lipid metabolism and deposition by influencing caffeine metabolism through Lachnospiraceae_NK4A 136_group and norank_f_Lachnospiraceae.To sum up,FTEs supplementation can improve the obesity induced by HFD,which mainly manifested in reducing body weight and depostion of fat,improving the disorder of lipid and glucose metabolism,and regulating the structural diversity of intestinal microbiota.Therefore,one of the mechanisms of FTEs intervention in high-fat diet induced obesity is to regulate the structure of intestinal microbiota and improve metabolism.Except for gut microbiota,FTEs regulated lipid metabolism and deposition by affecting the metabolites of body,while the pathway and mechanism require further research.