Mechanism Of Rutin Improving Obesity Via Regulating Intestinal Flora

Obesity is defined as excess accumulation of body fat.The energy imbalance between the body’s calorie intake and expenditure can lead to abnormal or excessive fat accumulation which can seriously affect health when it exceeds 30% of body weight.Diet control with exercise or drug therapy is now the mainstream way to lose weight.However,these methods are difficult to maintain for a long time with a high rate of weight regain and absence of continued weight loss.Therefore,we are in urgent need for an effective treatment for obesity.Intestinal flora is an emerging factor that can affect obesity and metabolic homeostasis in mammals.Dysfunction of intestinal flora can increase the risk of obesity and its complications.Eating pattern has been shown to have potential impact on the intestinal flora.Therefore,it is increasingly considered that correcting intestinal biologic disorders through pharmacological or nutritional interventions may be a promising strategy for treating obesity and related metabolic syndrome.Previous studies have suggested that flavonoid may be potential substrates for intestinal flora due to their low bioavailability and toxicity.Rutin,a kind of natural flavonoids widely existing in the plant kingdom,has also shown great potential in terms of antiobesity effect.However,the biological mechanism of its antiobesity properties remains unclear.The main research contents of this experiment are(1)To determine the effects of rutin on weight loss in HFD-induced obese mice;(2)To investigate whether rutin could improve the intestinal flora disorders;(3)To explore the potential link between the regulation of intestinal flora and the metabolic benefits given by rutin.The results are as follows:1.Obesity model was established by feeding mice with HFD.Rutin+HFD group were administered with rutin orally.Metabolic indexes were detected 16 weeks later.The results indicated that rutin could reduce HFD-induced weight gain,blood glucose and lipid metabolism,as well as liver injury.2.Rutin treatment could reduce lipid accumulation in epididymal fat and liver and suppress the development of nonalcoholic fat induced by HFD.Analysis of the expression of genes related to lipid metabolism consistently showed that rutin supplementation inhibited the expression of genes related to fatty acid transport and adipogenesis,and upregulated the expression of genes related to lipid decomposition and lipid oxidation in liver.In addition,rutin treatment could alleviate chronic inflammation induced by obesity and reduce serum free fatty acid and glycerol levels caused by fat inflammation.These results suggest that rutin was effective on reducing fat accumulation and low inflammation.3.Rutin treatment could protect intestinal epithelial integrity and ameliorate local inflammation as well as metabolic endotoxemia by regulating the TLR/ NF-κB pathway.4.16 S rRNA gene sequencing results of fecal samples showed that the flora richness and structure of Rutin+HFD group were more similar to that of healthy mice.At the phylum level,rutin supplementation reversed the Firmicutes/Bacteroides ratio induced by HFD and ormalized the relative abundance of Verrucomicrobia,and Proteobacteria.Further redundancy analysis and cluster analysis showed that Rutin(HFD)group significantly reduced the abundance of 29 OTU related to Lachnospiraceae,Ruminococcaceae and Erysipelaceae and increased the abundance of 24 OTU related to Roseburia,Bacteroides,Alistipes,Parasutterella and Akkermansia.Spearman analysis found 12 rutin-altered genera significantly associated with at least one obesity parameter.These results suggested that rutin may exert beneficial metabolic properties by regulating intestinal flora.5.To explore whether the potential effects of rutin can only be achieved in the presence of intestinal flora.We added broad-spectrum antibiotics to drinking water of HFD mice to remove endogenous microorganisms,and rutin was treated orally.Our results indicated that intragastric administration of rutin exhibited no effect on weight gain and fat accumulation due to a long-term antibiotic treatment.Therefore,it can be concluded that the antiobesity effect of rutin depends on the presence of intestinal flora.6.Fecal microbiota transplantation(FMT)experiment was further conducted to prove that rutin plays an anti-obesity role by regulating intestinal flora.The results of this study indicated that HFD weight gain,insulin resistance and lipid disorders were reduced or mitigated accompanied with improvement of epididymal fat and liver lipid deposition in HFD mice.Meanwhile,HFD mice receiving faecal transplants from Rutin+HFD group had stronger intestinal barrier function and lower local inflammation compared with those receiving faecal transplants from HFD group.In conclusion,our study confirms that metabolic phenotypes in donor mice can be reproduced in their corresponding recipient mice and supports the idea that intestinal flora mediates rutin’s metabolic protection.7.The results of 16 S r RNA sequencing showed that there were significant differences in intestinal microbial community between the two recipient groups.The abundance of Bacteroidetes and Verrucomicrophyla were increased in the recipient mice receiving fecal transplantation from Rutin+HFD group compared with HFD recievers,while that of Firmicutes and Proteobacteria were decreased.The analysis of community composition indicated that the genus level of Akkermansia,Bacteroides and Alistipes were increased and that of Lachnospiraceae＿NK4A136＿group,Lactobacillus and Faecalibaculum were significantly reduced in Rutin+HFD recievers.LEf Se analysis confirmed that Lachnospiraceae,Lachtobacilliaceae,Bacteroideaceae,Bacteroideaceae-S24 Group-7,Riskenellaceae and Verrucomicrobiaceae were the dominant phylotypes contributing to the differences between the intestinal flora of the two groups.Therefore,we found that the intestinal flora of recipient mice was similar to that of donor mice after FMT,suggesting that the beneficial effects observed in recipient mice require colonization of intestinal flora in donor mice.In summary,our study provides sufficient evidences in support of the antiobesity effect of rutin,which were mediated by the modulation of intestinal flora,restoration of the gut barrier,reduction of metabolic endotoxemia and chronic inflammation.We conclude that rutin might serve as a prebiotic agent to target the intestinal flora against the development of obesity and metabolic syndrome.