糖尿病大鼠肝脏组织中维生素D受体表达与血清25-羟维生素D相关性研究

Study on the correlation between vitamin D receptor expression in liver tissue and serum 25(OH) D level in diabetic rats

目的检测T2DM大鼠肝脏中维生素D受体(VDR)mRNA及蛋白表达,探讨T2DM大鼠肝脏VDR表达及血清25-羟维生素D[25(OH)D]与代谢指标的相关性。方法取60只健康雄性Wistar大鼠,随机分成T2DM组(n=30)和正常对照(NC)组(n=30)。T2DM组予高脂高胆固醇饲料喂养4周后,禁食16 h,按30 mg/kg单次腹腔注射STZ,72 h后尾静脉采血测血糖,以血糖浓度>16.7mmol/L作为糖尿病模型造模成功的标准。ELISA测定血清25(OH)D水平,RT-PCR和Western blot分别检测两组肝脏组织中VDR mRNA及蛋白表达。Spearman相关分析T2DM组血清25(OH)D与FPG、F1ns、FFA、TG、TC、HOMA-IR的关系。结果与NC组比较,T2DM组肝脏中VDR mRNA及蛋白表达增高[(2.15±0.25)vs(8.26±2.23),(0.317±0.085)vs(0.542±0.135)],血清25(OH)D水平降低[(43.6±12.3)vs(21.3±6.7)ng/ml],血清FFA、TG、TC、LDL-C、FIns、HOMA-IR增高(P<0.05)。相关性分析显示,血清25(OH)D与FFA、TG、FIns、HOMA-IR呈负相关,与HDL-C呈正相关(P<0.05)。结论 T2DM大鼠肝脏组织中VDR mRNA及蛋白表达增加,而血清25(OH)D降低。血清25(OH)D降低可能会反馈性促进肝脏VDR表达,并可能进一步导致肝脏IR及糖脂代谢异常。

Objective To detect the vitamin D receptor（VDR） mRNA and its protein expression in liver tissue of type 2 diabetic rats and explore the correlation of vitamin D receptor expression and the level of serum 25（OH） D with metabolic index.Methods A total of 60 healthy male Wistar rats were randomly divided into two groups：type 2 diabetes mellitus group（T2DM group,n=30） and normal control group（NC group,n= 30）.T2 DM group were treated with high fat and high cholesterol diet for 4 weeks.Then after fasting for 16 hours,this group was treated with intraperitoneal injection of streptozotocin 30mg/kg.Blood was collected from tail vein and blood glucose was tested 72 hours after injection.Blood glucose concentration 〉16.7 mmol/L was regarded as successful diabetic model.Enzyme linked immunosorbent assay（ELISA） method was used to detect the levels of serum 25（OH） D.The expression of VDR mRNA and its protein was detect by real-time polymerase chain reaction（RT-PCR） and Western blot respectively.The relationship between level of serum 25（OH） D and fasting glucose（FPG）,fasting insulin（FIns）,free fatty acid（FFA）,triglyceride（TG）,total cholesterol（TC）,total cholesterol（TG）,and insulin resistance index（HOMA-IR） in type 2 diabetic rats analyzed.Results The expression of VDR mRNA and its protein significantly increased in T2 DM group than in NC group[（8.26 ± 2.23） vs（2.15 ± 0.25）,（0.542 ± 0.135） vs（0.317 ± 0.085）,P〈0.05）;serum 25（OH） D level significantly decreased in T2 DM group than in NC group[（21.3 ± 6.7） vs（43.6 ± 12.3） ng/ml,P〈0.05];serum FFA,TG,FIns,HOMA-IR were significantly higher in T2 DM group than in NC group（P〈0.05）.Serum25（OH） D was negatively correlated with FFA,TG,FIns and HOMA-IR and positively correlated with HDL-C（P〈0.05）.Conclusion The expression of VDR mRNA and its protein significantly increases,while the level of serum 25（OH） D significantly decreases in liver tissue of type 2 diabetic rats.The decrease of serum 25（OH） D may promote the expression of VDR in liver,and may lead to hepatic insulin resistance and glucose and lipid metabolic disorders.