| Objectives To observe the hypoglycemic effect of D-chiro-inositol?DCI?on db/db mice with type 2 diabetes mellitus and the inhibition of liver injury,and to explore the associated underlying mechanisms.Methods 1 According to blood glucose and body weight,db/db mice were randomly divided into model control group?MCG?,high-dose DCI group(HDCIG,70 mg·kg-1·d-1),and low-dose DCI group(LDCIG,35 mg·kg-1·d-1).db/m mice were used as normal control group?NCG?.Gavage administration for 6 weeks,changes in blood glucose in each group were measured during the period;the contents of insulin?INS?,C peptide,aspartate aminotransferase?AST?and alanine aminotransferase?ALT?in serum were measured;the changes of liver tissue morphology and structure were be observed by HE staining,Masson staining,oil red O staining and transmission electron microscopy;the protein expression of glucose transporters 4?GLUT4?in liver tissue was detected by immunohistochemistry staining,and insulin receptor?IR?,and insulin receptor substrate 2?IRS2?were detected by Western Blot.2 To further observe the effect of DCI on glucose metabolism in db/db mice and explore the related mechanism.The changes of blood glucose were measured in each group;he contents of INS,glycated serum proteins?GSP?,and advanced glycation end products?AGEs?in serum were measured;liver glycogen content was detected by PAS staining and microplate method;the protein expression of IRS2,phosphoinositide 3 kinase?PI3K?,protein kinase B?AKT?,phospho-AKT?S473??P-AKT?,GLUT4 and glycogen synthase kinase 3??GSK3??in liver tissue was detected by Immunohistochemistry staining and Western Blot;The m RNA expression of IRS2,PI3 K,AKT,GLUT4 and GSK3? was detected by PCR.3 DCI was applied to Hep G2 cells,and the proliferative activity of Hep G2 cells was measured after DCI intervention in different concentrations;Hep G2 cells were divided into normal control group,high glucose control group and different concentrations of DCI group to measure glucose consumption;IRS2 protein expression was determined by immunofluorescence staining and flow cytometry.Results 1 Study on the effect of DCI on hypoglycemic and liver protective in db/db mice: 1)After the first administration 2 h and 4 h,the blood glucose level in HDCIG was significantly lower than that in MCG?P<0.01?;the random blood glucose level in MCG increased gradually with the increase of weeks,and the increase of blood glucose levels in the administration groups was suppressed?P<0.01?.2)There was no significant difference in the contents of INS and C peptide levels in each group;The levels of AST and ALT in MCG were higher than those in NCG?P<0.05,P<0.01?,and there was no significant decrease in the administration groups.3)Observation by light microscope and transmission electron microscope showed that hepatic tissue cells in MCG had severe edema,steatosis and fibrosis,severe organelle damage,and the structural state of the liver tissue in HDCIG and LDCIG improved to varying degrees.4)The protein levels of GLUT4,IR and IRS2 in liver tissue of MCG were significantly lower than those of NCG?P<0.01?;compared with MCG,the protein levels of GLUT4,IR and IRS2 in HDCIG were increased in varying degrees?P<0.01?,and IRS2 protein expression was significantly increased in LDCIG?P<0.01?.2 The effect and mechanism of DCI on glucose metabolism in db/db mice: 1)After the first administration of DCI,the blood glucose in HDCIG was significantly lower than that in MCG?1 h and 2 h,P<0.05;4 h,P<0.01?;the random blood glucose level in MCG gradually increased with the number of observation weeks,and the blood glucose levels in HDCIG and LDCIG decreased significantly?4 weeks and 6 weeks,P<0.01?;in oral glucose tolerance test,the AUC results of the administration groups were lower than that in MCG?P<0.01?;in the 24-hour blood glucose monitoring,the blood glucose level of each point in the administration groups was significantly higher than that in MCG,and the blood glucose result in HDCIG was lower?P<0.01?.2)There was no significant difference in serum INS levels among the groups;the contents of GSP and AGEs in MCG was higher than that in NCG?P<0.05?,and HDCIG was significantly lower than that in MCG?P<0.05?.Compared with MCG,LDCIG had different degrees of reduction,and the results of AGEs were significantly different?P<0.05?.3)There was a significant difference in the content of liver glycogen between MCG and NCG?P<0.01?,and HDCIG was significantly higher than MCG?P<0.05?.4)Compared with NCG,the expression protein levels of IRS2,PI3 K,AKT,P-AKT,and GLUT4 in liver tissue of MCG were reduced?P<0.01?,and the expression of related proteins in the administration groups was increased to varying degrees compared with MCG;the expression of GSK3? protein in MCG was significantly higher than that in NCG?P<0.01?,and higher than that in HDCIG and LDCIG.5)The m RNA levels of IRS2,PI3 K,AKT and GLUT4 in MCG were lower than those in NCG,and the results in HDCIG and LDCIG were significantly higher than those in MCG;the level of GSK3? m RNA in MCG was higher than that in NCG?P<0.01?,and the levels of GSK3? m RNA in HDCIG and LDCIG were decreased?P<0.05?.3 The effect of DCI on glucose consumption and IRS2 protein expression in Hep G2 cells stimulated by high glucose: 1)When the concentration of DCI was in the range of 0-50 ?g·m L-1,the cell viability of Hep G2 cells increased in a concentration-dependent manner.2)The glucose consumption of Hep G2 cells in different DCI administration groups was significantly higher than that in the high glucose control group?P<0.01?.3)The protein expression of IRS2 in 32 ?g·m L-1 DCI administration group was significantly higher than that in high glucose control group?P<0.01?.Conclusions 1 DCI has the effect of reducing blood glucose,improving glucose tolerance,and promoting blood glucose stabilization in db/db mice with type 2 diabetes mellitus.2 DCI has an inhibitory effect on hepatic damage in type 2 diabetic db/db mice,inhibits steatosis and fibrosis in liver tissue,and promotes glycogen synthesis in liver tissue.3 The mechanism of DCI improving glucose metabolism and protecting the liver may be related to its promotion of IR,IRS2,PI3 K,AKT,P-AKT and GLUT4 protein expression,inhibition of GSK3? protein expression,acceleration of insulin signal transduction,and increase of glucose consumption.Figure 20;Table 14;Reference 112... |
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