Protective role of Vitamin D in diabetic rats / 中华实用儿科临床杂志

ABSTRACT

Objective To investigate the protective effect of Vitamin D (VitD) on diabetic rats,and whether the protective mechanism is associated with the expression of nuclear factor kappa B (NF-κB) and insulin resistance (IR).Methods Diabetic Wistar rats were established by intraperitoneal injection of streptozotocin,and randomly divided into diabetic group,VitD treatment group (treatment group).Normal rats were served as normal control group.Treatment group was treated with VitD for 8 weeks.The levels of 24 h urinary protein (24 h UP),fasting plasma glucose (FPG),plasma insulin (p-Ins),plasma adiponectin (p-Adi),plasma glucagon (p-Gln) were measured.Tumor necrosis factor alpha (TNF-α),monocyte chemotactic protein 1 (MCP-1),interleukin-6 (IL-6) were determinated in renal cortical homogenate.The activity of NF-κB was evaluated by electrophoretic mobility shift assay.The mRNA expressions of glucose transporter protein 1 (GLUT1) and GLUT4 in renal cortex were detected by reverse transcriptase (RT)-PCR.Western blot analysis was performed to measure the phosphorylation of NF-κB and its inhibitor I kappa Balpha (IκBα),insulin receptor substrate protein 1 (IRS1),phosphatidylinositol 3 kinase (PI3K),p38 mitogen activated protein kinase (p38MAPK).Results Compared with the normal control group,24 h UP,FPG,p-Ins,p-Gln were significantly increased,and inflammatory markers and the expression of GLUT1 elevated in renal cortex in DM group,there were significant differences(all P ＜0.01).The activity of NF-κB (P ＜0.01) and the phosphorylation of NF-κB p65 and p38MAPK were elevated (all P ＜ 0.01),and phosphorylation of IκBα,IRS1,PI3K were decreased (all P ＜ 0.05,0.01) in diabetic group compared with those of normal control group.VitD treatment could ameliorate urine protein,increase p-Adi,reduce inflammatory markers and NF-κB activity (P ＜ 0.01),maintain GLUT1 expression,but had no effect on GLUT4 expression in renal cortical,attenuate NF-κB p65,p38MAPK phosphorylation (all P ＜ 0.05),partly restore IκBα,IRS1,PI3 K phosphorylation in diabetic rats (all P ＜ 0.05,0.01).Conclusions Protective role of VitD is associated with inhibiting the expression of NF-κB and reducing the insulin resistance in diabetes.