Vitamin D induces nitric oxide production in cultured endothelial cells / 中华实用儿科临床杂志

Objective To test the effects of Vitamin D (VitD) on endothelial nitric oxide(NO) production and to study the signal pathway leading to NO release.Methods In vitro cultured human umbilical vein endothelial cells (HUVEC) were treated with various concentrations of VitD(0 mmol/L,0.01 mmol/L,0.10 mmol/L,1.00 mmol/L,10.00 mmol/L) for 60 min,and VitD at concentration of 1.00 mmol/L at different time points (30 min,60 min,90 min,120 min).The effect of VitD on NO production in presence of VitD receptor(VDR) agonist(ZK191784) or antagonist(ZK159222) for 60 min were examined in cell culture supernatant with kit for the detection of nitric oxide fluorescent probe(DAF-FM DA).HUVEC was cultured with VitD in presence of VDR agonist or antagonist for 60 min,and the effect of VitD on NO production with DAF-FM DA and the protein expression and phosphorylation of Caveolin-1 and endothelial nitric oxide synthase(eNOS) were detected by Western blot,respectively.Results VitD caused a concentration-dependent increase in NO production.The maximum effect was observed at a concentration of 1.0 mmol/L and the optimal time of stimulation was 60 min.Effects induced by VitD were enhanced by VDR agonist,and abolished by antagonist.VitD and VDR agonist maintained the expression of Caveolin-1 at the same low phosphorylation level the same as normal,increased the phosphorylated level of eNOS.However,VDR antagonist increased the phosphorylation of caveolin-l,but reduced the level of eNOS phosphorylation,respectively.Conclusions VitD can induce a significant increase in endothelial NO production through VDR.VitD interaction with VDR causes the low phosphorylation of caveolin-1 leading to eNOS activation and NO production.

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

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.

Protective effect of vitamin D on high glucose-induced podocyte insulin resistance / 临床儿科杂志

Objectives To study the protective effects of vitamin D (VitD) on podocyte insulin resistance and its mecha-nisms. Methods Immortalized mouse podocytes in vitro were randomly divided into 4 groups:podocytes+5 mmol/L glucose group (group A);podocytes+5 mmol/L glucose+1 nmol/L propylene glycol group (group B);podocytes+30 mmol/L glucose+1 nmol/L propylene glycol group (group C); podocytes+30 mmol/L glucose+1 nmol/L propylene glycol+1 nmol/L VitD group (group D). The percentage of podocyte apoptosis was determined after 48 h of incubation. Podocyte viability was assessed by MTT assay. The mRNA expressions of vitamin D receptor (VDR) and insulin receptor substrate protein 1 (IRS1) in podocyte were detected by RT-PCR. Western blot analysis was performed to measure the protein levels of p-IRS1/IRS, p-Akt/Akt and p-ERK1/2/ERK1/2. Results There were significant differences in apoptosis percentage, viability and the expression of VDR, IRS1, p-ERK1/2 of podoctyes(P0.05). Compared with group A, B , and D, the percentage of podocyte apoptosis in group C was significantly increased, the cell viabi-lity was decreased, the expressions of VDR and IRS1 mRNA and p-IRS1 and p-Akt proteins were down-regulated, whereas p-ERK1/2 was up-regulated in group C. The levels of p-IRS1/IRS1, p-Akt/Akt, p-ERK1/2/ERK1/2 had no statistical differences in group A, B, and D (P>0.05). Conclusions VitD-VDR system alleviates podocyte apoptosis induced by high glucose, and acti-vates insulin signaling pathway and counteracts insulin resistance signal to improve podocyte insulin resistance.

Phosphorylation of p38MAPK in hyperoxia-induced lung injury of new-born rats / 第三军医大学学报

Objective To investigate the expression and significance of p38 mitogen-activated protein kinase (p38MAPK) in hyperoxia-induced lung injury of new-born rats. Methods Totally 160 rats at the age of 12 h were randomly and equally divided into air control group, hyperoxia-induced lung injury group, hyperoxia-induced lung injury+SB203580 group and hyperoxia-induced lung injury + normal saline group. After the injury was inflicted, SB203580 or normal saline at same volume was given intraperitoneally at 5 mg/kg. After the rats were executed at the time points of 12, 24, 72 h and 1 week after the model establishment, the right upper lungs were resected for histopathology, right below lungs for wet weight/dry weight, and left lungs for detecting the expression of p38MAPK by Western blot analysis. Results Hyperoxia-induced lung injury model were established successfully after 72 h by exposure to hyperoxia. No p38MAPK expression was observed in air control group. In hyperoxia-induced lung injury group p38MAPK was detected from 12 h, reached to the peak at 72 h, and decreased 1 week later, and its expression was significantly higher in this group and normal saline group than in SB203580 group. Conclusion p38MAPK is involved in the process of hyperoxia-induced lung injury, and the injury can be relieved by treatment of SB203580.