The Effect And Preliminary Mechanism Of Dhp On Glycose Metabolism In Type 2 Diabetic Mice

Due to diet habits and lifestyle changes,the incidence of diabetes in China is rapidly rising recently.Diabetes and its complications are increasingly threatening people’s health,causing a heavy economic burden on families and society.Therefore,searching anti-diabetes drugs with low cost,good therapeutic effect,and low side effects is of great significance and imminent.Our previous in vitro studies found that Dhp has a protective effect on high glucose and high lipid damaged islet β cell line INS-1 cells,The main purpose of this study was to further explore in vivo the effect of Dhp on glucose metabolism in type 2 diabetic mice and to explore the preliminary mechanism.In this study,we took 60 C57 BL / 6J mice which were fed sterile,12 of them as control group fed with normal diet,and the remaining fed with 45%fat diet for three months to establish Type 2 diabetes mice model.From the beginning of the8 th week since high fat feeding,fasting,blood glucosewas measured every two weeks and when fasting blood glucose values of high fat feeding mice were all above 7 mmol/L,the diabetic mice were established successfully and were randomly divided into four groups:High Fat Diet(HFD)group,Dhp 0.5,1.0,2.0 mg/kg dose group.All the animals were injected intraperitoneally with Dhp every other day for 6 weeks,and blood glucose was measured after 4 weeks of administration.One week before the end of the experiment,mice were weighted and GTT and ITT mice were performed following 8 hours fasting.Then all mice were anesthesized by intraperitoneal injection of chloral hydrate,and heart blood were collected to measure relevant index and organs were removed for morphological observation anddetecting correlated.The main results are as follows:1.Dhp reduces body weight and fasting blood glucose in type 2 diabetic mice.The results showed that compared with the control group,the weight of mice in the HFD group was significantly increased(P<0.001),and the body weight of the Dhp 2mg/kg group was significantly lower than that of the HFD group(P<0.05).Compared with the control group,fasting blood glucose of HFD group was significantly higher(P<0.001),but the blood glucose of Dhp 0.5,1.0,2.0 mg/kg dose group was significantly lower than that of HFD group(P<0.01 or P<0.001).These data indicate that Dhp can reduce body weight and blood glucose in type 2 diabetic mice.2.Dhp can improve blood glucose regulation in type 2 diabetic mice and effectively relieve their insulin resistance status.After injection of glucose or insulin,compared with the control group,the mice in the HFD group exhibited significant glucose and insulin intolerance.After 90 min of intraperitoneal injection of glucose or insulin,the blood glucose level of Dhp2 mg/kg group returned to normal level,and the change trend was similar to that of the control group.The level of insulin and C-P in the serum of mice was detected by ELISA.Compared with the control group,serum insulin and C-P content of HFD group mice were significant increased and insulin resistence appeared.However,serum insulin and C-P content of different doses of Dhp treated mice returned to normal levels.These results reveal that Dhp can improve the hyperglycemia and insulin resistance of type 2 diabetic mice.3.Dhp can improve the antioxidant capacity of type 2 diabetic mice.Compared with the control group,superoxide dismutase(SOD),glutathione peroxidase(GSH-PX),catalase(CAT),and Total-antioxidant capacity(T-AOC)levels of HFD group were decreased significantly,and malondialdehyde(MDA)content increased significantly.The different dose of Dhp can increase the levels of SOD,GSH-PX,CAT and T-AOC and reduce the content of MDA in pancreas homogenate.This result proves that Dhp can improve the antioxidant capacity of type 2 diabetic mice.4.Dhp can improve muscle glycogen and liver glycogen synthesis ability in type 2diabetic mice.Compared with the control group,glycogen content of muscle and liver homogenates of the HFD group was significantly decreased,while the different dose of Dhp increased the glycogen content in muscle and liver homogenates.This indicates that Dhp can improve the ability of muscle glycogen and hepatic glycogen synthesis in type 2 diabetic mice.5.Dhp restores expression of important transcription factors in pancreatic cells in type 2diabetic mice.Western Blot experiments showed that compared with the control group,the expression of Pdx-1 and Nkx2.2 of HFD group were significantly decreased,while the expression of Pdx-1 and Nkx2.2 of Dhp group were significantly higher than that of HFD group.Immunofluorescence staining showed that compared with the control group,the expression of Nkx2.2,Nkx6.1 and Maf A of HFD mice was significantly decreased,while the expression of Nkx2.2,Nkx6.1 and Maf A of the different dose of Dhp group were higher than that of the HFD group.This study suggests that Dhp may have the function to protect and restore function and vitality of pancreatic β-cells.6.Dhp can improve the insulin signaling pathway and glucose metabolism signaling pathway in type 2 diabetic mice.The Western Blot of mice pancreatic tissue protein showed that compared with the control group,the level of p AKT in the HFD group was significantly decreased and the insulin signaling pathway was impaired,while the level of p AKT in the Dhp group was higher than that in the HFD group.The Western Blot of mice muscle tissue protein showed that compared with the control group,the levels of p AMPK and GLUT4 in the HFD group were significantly decreased,and the glucose metabolism pathway was impaired,while the levels of p AMPK and GLUT4 in the Dhp group were higher than those in the HFD group.It shows that Dhp can improve insulin signal pathway and glucose metabolism signal pathway in type 2 diabetic mice.7.Dhp can reduce the histopathological damage of pancreas and liver in type 2 diabetic mice.Compared with the control group,obvious pathological lesions were observed in the pancreas and liver tissues of the HFD group.Compared with the HFD group,there was no significant difference in the pathological changes of the Dhp 0.5 mg/kg group,while Dhp 1mg/kg,2 mg/kg can significantly reduce the pathological damage of pancreas and liver tissue.Compared with the control group,the islets of the HFD group became smaller and the number decreased,while the Dhp 1 mg/kg,2 mg/kg dose group increased the size of the pancreatic islets and increased the number of the islets.This suggests that Dhp can reduce the histopathological damage of pancreas and liver in type 2 diabetic mice and might maintain functional integrity of pancreas through promoting islet regeneration.In summary,Dhp can significantly improve the hyperglycemia and insulin resistance in type 2 diabetic mice,correct glucose metabolism disorders,and protect the structure and function of the pancreas.The mechanism may be achieved by fighting oxidative damage of free radicals,restoring the number and function of islet beta cells,activating the insulin signaling pathway and correct glucose metabolism signaling pathway.