| With the changes in life style of human,the incidence and prevalence of the type 2 diabetes(T2D)continues to rise globally,which is a major chronic disease that seriously threatens human health.It is of great significance to seek new drugs with the character of safe,most effective,cheap and no side effects.In recent years,the important role of intestinal microbes in the pathogenesis of diabetes has been fully confirmed and the intestinal microbes are expected to be a new target for the treatment of T2 D in the future.Mannose oligosaccharide(MOS)is a new type of prebiotics,which can regulate gut microbiota and improve intestinal environment.Whether this regulation can help improve blood glucose in diabetic patients and whether it has an impact on the effect of hypoglycemic drugs has not yet been carried out.In this experiment,the hypoglycemic effect of MOS combined with metformin(MF)was investigated,and the hypoglycemic mechanism was analyzed from the aspect of intestinal microorganism.The main results are as follows:(1)Hypoglycemic effect evaluation for composite treatment of mannose oligosaccharides and metformin.The model of T2 D was induced by the combination of high fat diet and streptozotocin on C57BL/6J mice.After five weeks of treatment,MOS(8 g/kg,4 g/kg,2 g/kg)showed the trend of lowing fasting blood glucose(FBG),improving glucose tolerance,reducing HbA1 c and ameliorating HOMA-IR in a dose-dependent manner.Composite treatment(MF+MOS),including MFH(200 mg/kg)+MOSH(8g/kg)、MFH(200 mg/kg)+MOSM(4 g/kg)、MFL(75 mg/kg)+MOSH(8 g/kg)、MFL(75 mg/kg)+ MOSM(4 g/kg)treatment,demonstrated synergistic effects on improving biochemical index mentioned above and the hypoglycemic effect of MF+MOS were superior to metformin or MOS single treatment.It is also found that MF+MOS could ameliorate the impaired islet cells,reduce the vacuolation of liver tissue,increase the number of goblet cells and reduce the infiltration of inflammatory cells in in the ileum tissue.(2)The effect of MF+MOS on insulin signaling pathway.The gene and protein expression of IR/IRS-1/PI3K/AKT/Glut4 in skeletal muscle significantly up-regulated by MF+MOS treatment,indicating that MF+MOS treatment could enhance the sensitivity of insulin and promote the utilization of glucose in the tissue of skeletal muscle,so as to achieve significant hypoglycemic effect.(3)The effect of MF+MOS on gut microbiota.The microorganism genome of mice feces in each group was extracted.The 16 S rRNA amplified subsequence analysis showed that the diversity and abundance of gut microbiota were decreased in diabetic mice while increased after the treatment of MF+MOS.Cluster analysis showed that the ability on regulating gut bacteria of MF+MOS were superior to that of MF alone.In phylum level,MF+MOS treatment increased the Verrucomicrobia.At the genus level,LEfSe(Linear discriminant analysis Effect Size)analysis showed that MFH+MOSH treatment enriched Bifidobacterium,Akkermansia,Allobaculum,Sutterella,Anaerotruncus and Anaerostipes.At the OTU level,we found 108 OTUs which was significantly different between the model control group and normal group.16 OTUs were reversed after MF+MOS treatment,which was more than OTUs(6 OTUs)reversed by MF alone;In addition,the correlation between OTUs and the biochemical indexes in MF+MOS goup was more closely related than MF group.Prediction of gene function showed that genes involved the metabolic function of bacteria in the diabetic model group was significantly lower than the normal group,while the carbohydrate metabolism was significantly higher than the normal group.Further analysis of the energy metabolism and carbohydrate metabolism,we found that methane metabolism and glycolysis/gluconeogenesis metabolism was significantly reversed by MF+MOS treatment,.In conclusion,MF+MOS treatment achieve better hypoglycemic effect than single metformin or MOS treatment.This could be closely related to the overall structure and composition of gut microbiota,as well as the change in abundance of the key OTUs. |
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