| Objective:To compare the therapeutic effect of astragalus polysaccharides?APS?and metformin hydrochloride?MH?on experimental type 2 diabetic rats,and to explore the mechanism of astragalus polysaccharide treatment of type 2 diabetes mellitus.Methods:1.Comparative study on the therapeutic effects of APS and MH on type 2 diabetic ratsThe rat model of type 2 diabetes mellitus was induced by the method of combination of high fat diet and Streptozotocin?STZ,30mg/kg?.Sprague Dawley?SD?rats were randomly divided into normal group?NC?,type 2 diabetes mellitus group?T2DM?,APS treatment group and MH treatment group.Fasting blood glucose?FBG?of all rats was determined in 4 time points,including before and one week after STZ injection,and 4 and 8 weeks after drug treatment.Water intake,diet uptake,urine volume and body weight of each rat were detected,and triglyceride?TG?,total cholesterol?TC?,high density lipoprotein cholesterol?HLD-C?,low density lipoprotein cholesterol?LDL-C?,alanine aminotrans ferase?ALT?and total protein?TP?content in rat serum was measured.2.Effect of APS on postprandial blood glucose in type 2 diabetic rats and its inhibitory effect on ?-amylaseAfter 12 hours of fasting,the normal rat+distilled water group?NC+d H2O?and type2 diabetes mellitus rat+distilled water?T2DM+d H2O?were given starch solution-distilled water,APS intervention group?NC+APS?and APS treatment group?T2DM+APS?given starch-700mg/kg astragalus polysaccharide Mixture,the FBG and postprandial blood glucose were measured.3,5-dinitrosalicylic acid?DNS?colorimetric method was used to determine the inhibitory rate of different concentrations APS to ?-amylase.The fasting insulin levels?FINS?were determined by Enzyme linked immunosorbent assay?ELISA?and the insulin secretion index HOMA-? was used to evaluate the function of islet ? cells,HOMA-?=20×FINS/?FBG-3.5?.Hematoxylin-eosin staining to observe the histopathological features of the pancreas.The expression of insulin / ki67 in pancreatic tissue of NC group,T2 DM group and APS treatment group was detected by immunohistochemical staining.The total number of islet ? cells and the number of newborn islet ? cells were measured.4.Effect of APS on miR-32-5P in type 2 diabetic rats and its biological information analysisThe miRNA expression profiles in the serum of T2 DM group and APS treatment group were analyzed by miRNA gene chip technique.The differentially expressed miRNAs were screened out.The RT-PCR technique was used to detect the expression of the differentially expressed serum miRNAs in the pancreas tissue of T2 DM group and APS treatment group;and the target gene is predicted and its function and pathway are analyzed finally.Results:1.One week after the injection of STZ,model rats showed higher than 11.0 mmol/l FBG and accompanied by the typical symptoms of type 2 diabetes mellitus;Four weeks after drug intervention,FBG of rats was significantly decreased in MH treatment group?p<0.05?,and showed declining trend in APS treatment group.However,the symptoms of type 2 diabetes mellitus had no obvious ameliorated in the two groups;After 8 weeks of drug intervention,the FBG of rats in the MH treatment group was not significantly decreased,TG and HLD-C were significantly reduced?p<0.05?,while the FBG in the APS treatment group continued to decline,and there was significant difference compared with that of type 2 diabetic rats?p<0.05?,.Moreover,water intake and diet uptake of rats obviously improved,TG and HDL-C also decreased significantly in APS treatment group?p<0.05?.2.Compared with NC+d H2 O group,the postprandial blood glucose of NC + APS was significantly decreased?p<0.05?.Compared with T2DM+d H2 O,the postprandial blood glucose of T2 DM + APS was significantly decreased?p<0.05?.The inhibitory rates of 0.20% APS,0.05% APS and 0.0125% APS on ?-amylase were 8.5%,7.1% and 6.3%respectively,and the inhibitory effect of APS on ?-amylase was dose-dependent.3.Compared with rats in NC group,rats in T2 DM group had significant increase in the FINS and HOMA-??p<0.05?;Compared with rats in T2 DM group,rats in APS treatment group had significant increase in the FINS and HOMA-??p<0.05?.Compared with rats in NC group,rats from T2 DM group showed significant atrophy in islet accompanied by loss of granular and vacuolar degeneration;Compared with rats in T2 DM group,rats in APS treatment group showed significant increase in islet volume accompanied by improvement of islet demyelination and vacuolar degeneration.Compared with NC group,the number of ? cells in islets of T2 DM group was significantly lower than that of NC group.Compared with T2 DM group,the number of ?cells in islets of APS treatment group was significantly higher than that in T2 DM group.Compared with T2 DM group,the total number of beta cells and the number of newborn ? cells in APS group were significantly higher than those in T2 DM group.4.A total of 7 differentially expressed serum miRNA were obtained,6 of which were down regulated,and the other were up-regulated,and it has been verified in the pancreas.The results showed that the expression of miR-32-5p in pancreatic tissue of rats in the APS treatment group was similar to that in serum.GO function annotation display:miR-32-5p mainly involves intracellular glucose balance,phosphatidylinositol phosphorylation,phosphatidylinosi tol-3-phosphate biosynthesis process,cell mitosis G1 phase,DNA replication initiation,cell cycle regulation,protein binding,transcription factor Binding,insulin receptor signal transduction and other molecular functions and biological processes.KEGG annotation display:miR-32-5p is mainly enriched in the pathway of phosphatidylinositol signaling pathway.Which is associated with cell proliferation,mainly related to PI3KR2 and CCNE2 gene.Conclusion:The mechanism of the APS in the treatment of type 2 diabetes,may be inconsistent with the APS are activated to restrain activity of alpha amylase,reduce postprandial blood sugar.The specific mechanism needs further study,may also be related to APS decrease the expression of miR-32-5p,regulate PI3K-AKT signaling pathway,promote islet beta cells proliferation,increased insulin levels. |
PDF Full Text Request