| Objective:1.To observe the influence of Ang-(1-7) on the morphology and function of islet tissue in type 2 diabetic rats;2.To compare blood glucose, the expression of serum insulin and angiotensin Ⅱ(Ang Ⅱ) and the change of protein and gene of the pancreatic duodenal homeobox-1(PDX-1) and glucose transporter-2(GLUT-2) in islet tissue of each group;3.To investigate whether Ang-(1-7) could improve the islet function in type 2diabetic rats by increasing the expression of PDX-1 and GLUT-2.Methods:34 healthy male Wistar rats of 8 weeks old, using normal diet fed for 2 weeks.Randomly selected 10 rats as normal control group(NC, n=10), to continue the normal diet until the end of the experiment. After 8 weeks of high-fat and high-calorie feeding, the remaining 24 rats were given intraperitoneal injection of STZ 30mg/kg to construct a model of type 2 diabetic rats. 20 successfully-induced diabetic rats were randomly divided into diabetic control(DM) group and Ang-(1-7) intervention[Ang-(1-7)] group, the number of rats in each group was 10. The rats in group Ang-(1-7) group were given Ang-(1-7) by subcutaneous injection of the neck for 8weeks, while the DM and NC group were given equal volume of normal saline. The levels of blood glucose, serum insulin and Ang Ⅱ were detected and homeostasis model assessment of insulin resistance index(Homa-IR) was calculated in each group.Using HE staining to observe and compare the morphology and structure of each rat’s islet tissues. Respectively using immunohistochemical staining method and real-timefluorescence quantitative PCR(RT-PCR) to detect the protein and m RNA expression of PDX-1 and GLUT-2, and quantitative analysis the results.Results:Compared with NC group, the body weight of rats in DM group was decreased(P < 0.05), blood glucose, serum AngⅡ levels and Homa-IR were increased(P <0.05), serum insulin levels were decreased(P < 0.05); the number of rat islet was decreased, the volume became small, the structure was damaged, the islet cells were reduced and quite irregular in shape, disordered arrangement. The protein expression of PDX-1, GLUT-2 in islet were decreased by 61.04% and 59.74%(P < 0.05), the m RNA expression were decreased by 64.60% and 52.94%(P < 0.05). Ang-(1-7)intervention group compared with DM group, the body weight of rats have no obvious changes(P > 0.05), but the blood glucose, serum AngⅡ levels and Homa-IR were all reduced(P < 0.05); serum insulin levels were increased(P < 0.05); rat islet morphology was irregular, but the boundaries is still clear, the number of islet cell was slightly increased, the structure damaged is improved compared with DM group, but did not recover to the NC group level. The protein expression of PDX-1, GLUT-2 in islet were increased by 55.97% and 53.05%(P < 0.05), the m RNA expression were increased by 68.85% and 50.69%(P < 0.05).Conclusions:Ang-(1-7) may increase the islet β cell synthesis and secretion of insulin,improve the function of islet β cell, and delay the progression of type 2 diabetes mellitus to a certain extent by increasing the expression of PDX-1 and GLUT-2. |
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