| The Tibetan Edgeworthia gardneri has a long history in China.According to the previous research of our laboratory,the water extract of Edgeworthia gardneri contains 29 substances,including polyphenols,polysaccharides and flavonoids,which have the effects of lowering blood sugar,anti-inflammatory and regulating intestinal flora.Previous experiments showed that water extract of Edgeworthia gardneri could improve the hyperglycemia of type 2 diabetes mellitus and regulate intestinal flora.However,the mechanism of action of water extract of Edgeworthia gardneri on type 2 diabetes mellitus based on intestinal flora has not been studied.Therefore,on this basis,this study took the water extract of Edgeworthia gardneri as the research object to establish a mouse model of type 2 diabetes,evaluate the hypoglycemic effect in mice,and further analyze the influence mechanism of water extract of Edgeworthia gardneri on type 2 diabetes from the perspective of intestinal flora.This study provides a new perspective on the way to treat diabetes.The main research work is as follows:(1)In this study,the previous extraction method was used to obtain the water extract of Edgeworthia gardneri,and the mouse model of type 2 diabetes was established by high fat diet for four weeks combined with intritoneal injection of streptozotocin for 5 day.35 mice were randomly divided into 7 groups(n=5): Control group(Control,CTL),type 2 diabetes Model group(Model,MOD),Edgeworthia gardneri water extract group(LWEG: 1 g/kg,HWEG: 3g/kg),antibiotic group(ANT-).Water in the antibiotic group was changed into antibiotic solution one week in advance,and then the mice were given continuous intragastric administration for four weeks.The experimental results show that the antibiotic concentration of fasting blood glucose(FBG)in mice after intervention,the amount of glucose tolerance(OGTT),total cholesterol(TC),triglyceride(TG)has alleviate,and insulin(INS),high density lipoprotein(HDL-C,LDL-C),viscera index to improve the effect is not apparent,the mice liver,fat,and the organization of the colon showed the effect of repair.The results of this study suggest that intestinal microbiota clearance with antibiotics cannot be used as a means of investigating whether intestinal microbiota improves the mechanism of action in type 2 diabetes.(2)The extraction method of Edgeworthia gardneri and the establishment of animal model were described above.Forty mice were randomly divided into 8 groups(n=5): Control group(Control,CTL),type 2 diabetes Model group(Model,MOD),Metformin group(Metformin,Met: 500 mg/kg),water extract of Edgeworthia gardneri(LWEG: 1 g/kg,HWEG: 3 g/kg),and corresponding Fecal bacteria transplantation group(FMT).After one week of intragastric administration,the feces of the treated mice were collected,and 200 μL for 28 days.The glucose and lipid metabolism and histopathological changes of the diabetic mice were observed.The results showed that the flora transplant mice decreased food intake,water quantity,and weight,and improve the FBG,HDL-C,LDL-C,TG,TC,INS,aspertate aminotransferase(AST),alanine aminotransferase(ALT),and other indicators,we can observe from the tissue biopsies,WEG and FMT group show,fat,liver,pancreas and colon tissue repair.The above experiments confirmed that FMT and WEG have similar effects on reducing blood glucose in diabetic mice,and the regulation of intestinal flora is a key link in the improvement of glucose metabolism in diabetic mice by WEG.(3)16S rRNA high-throughput sequencing was used to explore the effects of water extract of Edgeworthia gardneri on the richness and diversity of intestinal microflora of type 2 diabetic mice,and the key species related to the improvement of glucose metabolism by water extract of Edgeworthia gardneri were screened out.The content of short chain fatty acids(SCFAs)in cecal contents of mice was determined by HPLC,and the content of inflammatory factors and tight junction proteins in intestinal tissues were analyzed by fluorescence quantitative PCR,and the content of serum endotoxin was determined by enzyme linked immunoassay(ELISA)..Sequencing results showed that the structure and composition of intestinal microflora of type 2diabetic mice treated with WEG and FMT significantly changed,and the analysis of α-diversity and β-diversity of intestinal microflora of diabetic mice increased.The composition of intestinal microflora after WEG intervention was significantly different from that of the model group.From the phylum level,we observed that WEG could reduce the richness of Firmicutes and increase the abundance of Bacteroidetes and Actinobacteria in model mice.The abundance of Proteobacteria in model mice was significantly reduced after bacterial community transplantation.Through analysis of key bacterial genera,it was found that WEG and FMT could up-regulate the abundance of beneficial bacteria such as Allobaculum and Bifidobacterium.WEG and FMT increased the content of intestinal SCFAs,decreased inflammatory cytokines and increased the transcription level of tight junction protein,and significantly reduced the content of serum endotoxin.These results suggested that the water extract of Edgeworthia gardneri could alleviate the symptoms of type 2 diabetic mice by regulating the composition of intestinal microflora and the changes of key bacterial genera. |
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