吡格列酮对糖尿病大鼠肾组织podocalyxin表达的影响

Effect of pioglitazone on the expression of renal tissue podocalyxin in STZ-induced diabetic rats

目的观察不同剂量盐酸吡格列酮(PIO)对STZ诱导的糖尿病大鼠的肾脏保护作用及肾小球Podocalyxin(PCX)表达的影响方法链脲佐菌素(STZ)65 mg.kg-1腹腔注射后建立糖尿病大鼠模型后随机分为4组,分别为模型组(DM组,n=8)和不同剂量盐酸吡格列酮组(DR1、DR2、DR3组,PIO分别:10、20和30 mg.kg-1.d-1,各组n=8),并设正常对照组(NC组,n=8)。于0周及8周末测尿白蛋白(UAlb),尿视黄醇结合蛋白(URBP),尿沉渣PCX(UPCX)和尿肌酐(UCr)。每周监测血糖,8周末取血检测HbA1c,留取左肾观察病理变化,免疫组化及RT-PCR检测肾组织PCX蛋白及mRNA水平。结果①各组糖尿病大鼠各时间点血糖及8周末HbA1c明显高于NC组(均P<0.01),各糖尿病组间差异无统计学意义;②8周末DR1、DR2和DR3组UACR、URCR、肾脏肥大指数(KI)、基底膜厚度(GBMT)、足突融合率(FPFR)均明显低于DM组(均P<0.05),且DR2组和DR3组低于DR1组(均P<0.05);DR2组及DR3组UPCR明显低于DM组(P<0.01),DR1组轻度降低但差异无统计学意义;各PIO组肾组织PCX蛋白及mRNA水平明显高于DM组(P<0.01),且DR2组和DR3组PCX蛋白表达高于DR1组(P<0.05);③8周末,各糖尿病组大鼠Scr、BUN、TG、LDL-C均高于NC组,HDL-C低于NC组,各PIO组BUN、TG均明显低于模型组(P<0.05),DR2及DR3组HDL-C水平高于模型组(P<0.05)。④UPCR与UACR和KI呈正相关(r=0.86,r=0.833,P<0.01)。结论吡格列酮可减轻糖尿病大鼠肾脏损伤,该作用可能部分与其增加肾小球足细胞PCX蛋白和mRNA表达,抑制PCX随尿排泄有关,这一作用具有一定的剂量依赖性。

Aim To investigate the reno-protective effect of different dosages of hydrochloride pioglitazone and its effect on the expression of glomerular podocalyxin（PCX） in STZ-induced diabetic rats.Methods Diabetic models were established by a single injection of streptozotocin（STZ 65 mg·kg-1）.Diabetic rats were randomly divided into following four groups： diabetic rats without treatment（DM,diabetic model group,n=8）,10,20 and 30 mg·（kg·d）-1 pioglitazone（PIO）treated diabetic rats（group DR1,DR2 and DR3,n=8 respectively）.8 healthy rats were served as a normal control group（group NC）.Urinary albumin（UALB）,urinary retinol-bindingprotein（URBP）,urinary sediment PCX（UPCX） and urinary creatinine（UCr） were measured at 0 and the end of the 8th week.To eliminate the impact of urine volume,the parameters mentioned above were expressed as UACR,URCR,UPCR,respectively.At the end of the 8th week,HbA1c levels were assessed and the left kidney was microdissected for morphometric analysis.Renal tissue PCX mRNA and protein expression were determined by RT-PCR and immunohistochemistry respectively.Results ① The blood glucose levels throughout the study period along with HbA1c at the end of the 8th week in diabetic rats were significantly higher than those in group NC（P0.05）,whereas no significant differences were found between PIO-treated groups and group DM.②At the end of the 8th week,the levels of UACR,URCR,KI,glomerular basement membrane thickness（GBMT） and foot process fusion ratio（FPFR） decreased significantly in PIO-treated groups compared with group DM,while the variables mentioned above in group DR2 and DR3 groups were lower than those of DR1 group.In addition,the levels of UPCR in group DR2 and DR3 decreased when compared with group DM（P0.05）,whereas UPCR in group DR1 was slightly lower than that of DM group（P0.05）.Down-regulation of the mRNA and protein expression of PCX was inhibited by PIO-therapy,the levels of PCX protein both in group DR2 and DR3 were higher than that of DR1 group（P0.05）.③ At the end of the 8th week,the parameters including SCr,BUN,TG,LDL-C were significantly higher,whereas serum HDL-C was lower compared with those of group NC.Pioglitazone therapy markedly decreased the level of BUN and TG（P0.05）.Notably,HDL-C in group DR2 and DR3 were higher than group DR1（P0.05）.④ UPCR was positively correlated with UACR and KI respectively（r=0.868,r=0.833,P0.01）.Conclusion Pioglitazone can alleviate kidney injury of diabetic rats,which may be to some extent related to its functions in restraining the loss of PCX in the urine and inhibiting the down-regulation of the mRNA and protein expression of podocyte PCX in a dose-dependent mode.