Changes Of Intestinal Mucosal Barrier Structure And Endocrine Function In IGT Stage In Spontaneous Type 2 Diabetic Rats

ObjectiveThe incidence of diabetes has been increasing year by year,and China accounts for an important proportion.As an important stage in the development of diabetes,IGT has bothered large number of people,hence,it is important to explore its pathological features and conduct relevant analysis.Taking the spontaneous type 2Diabetic rats--ZDF rats(Zucker Diabetic Fatty rat,fa/fa)and normal ZL rats(Zucker Lean rats,fa / +)as experimental group(IGT group and diabetes group)and control groups,we explored the difference between the 3 groups in blood parameters and intestinal changes,to find out the metabolic characteristics of IGT rats.Methods20 male Specific pathogen Free ZDF rats of 6 weeks of age were induced by high fat diet(Purina # 5008)to IGT period,and then randomly selected 10 as IGT group.The rest of the rats(diabetes group)continued with high fat diet to diabetes.Five normal 6-week-old Zucker rats(Zucker Lean rats,fa / +)served as normal control group,and were also given high-fat diet.Finally,they were sacrificed together with diabetic rats.Weekly oral glucose tolerance test(OGTT)was used o to determine the progression of the disease.All diabetes group rats developed into diabetes mellitus was the end point.The changes of blood glucose and body weight were recorded and the levels of insulin(INS),glucagon(GC),lipopolysaccharide(LPS),glucagon-like peptide-1(GLP-1)and glucagon-like peptide-2(GLP-2)were measured by enzyme-linked immunosorbent assay(ELISA).HOMA-IR index was used to evaluate insulin resistance.The changes of intestinal flora were observed with16 SrDNA high-throughput sequencing method.Animals were sacrificed after the experiment,and we take intestinal tissues to observe the changes of intestinal mucosal morphlolgy,and the expression of tight junction proteins--occludin,ZO-1and inflammation indicators--NF-?B,TLR-4 and TNF-? in differrent groups.Results1.The results of model:After feeding high fat diet to all groups,the ZDF rats were all developed to IGT after 3 weeks(9 weeks old)and diabetes after 6 weeks(12weeks old);while none of ZL group developed to IGT or DM.2.General situation:The fasting blood glucose and body weight of ZDF rats increased gradually.Compared with normal ZL rats,the two indicators significantly higher in IGT group and diabetes group(P <0.05),while there was no statistically difference between IGT group and diabetes group.(P> 0.05).3.Blood index level: The levels of fasting plasma insulin in the three groups were IGT group> diabetes group> normal group,while the levels of glucagon and insulin resistance were gradually higher in the normal group,IGT group and diabetic group.Tthe results between groups were statistically significant(P < 0.05).Compared with normal ZL rats,plasma lipopolysaccharide significantly increased in IGT(P<0.05),whereas glucagon-like peptide-1 and glucagon-like peptide-2 levels in IGT decreased,and the results showed difference(P <0.05).There was no significant change in the above three indexes between IGT group and diabetic rats(P> 0.05).4.Intestinal mucosa morphology observed by HE staining: The intestinal villus in normal group arranged in neat rows,regular rules,with no edema of the lamina propria,showing a small amount of inflammatory cell infiltration.While IGT group and diabetes group had varying degrees of intestinal mucosal morphological changes,and diabetes group more serious.5.Immunohistochemistry: The expression of NF-?B,TLR-4 and TNF-? in normal group,IGT group and diabetes group increased gradually,while the expression of Occludin and ZO-1 decreased(P <0.05).6.16 SrDNA high-throughput sequencing to observe changes in intestinal flora structure: The intestinal flora diversity of normal group,IGT group,diabetic group decreased in turn.At the phylum level,the main components of intestinal flora in each group were Bacteroidetes and Firmicutes,but the ratio of Bacteroides / Firmicutes were gradually increased.At the genus level,Prevotella was significantly lower in the normal group than in the diabetes group,while Lactobacillus and Bacteroides were higher in the IGT group than the other two groups,and Clostridium,Roseburia,,and Ruminococcus relative abundance was gradually reduced in 3 groups.Conclusion1.The rat model of IGT and diabetes mellitus were successsfully prepared.2.At the IGT stage,plasma LPS level increased and GLP-1 and GLP-2 levels decreased,indicating that endotoxemia and other hormone abnormalities involved in blood glucose regulationduring IGT.3.Intestinal mucosal barrier was damaged and structure of intestinal flora changes in IGT.