C肽对糖尿病肾病大鼠肾小管间质氧化应激的影响

Effect of C peptide on tubulointerstitial oxidative stress in rats with diabetic nephropathy

目的:探讨C肽对链脲佐菌素诱导的糖尿病肾病大鼠肾小管间质氧化应激的影响。方法:腹腔注射链脲佐菌素的Wistar大鼠发展至糖尿病肾病后,随机分为对照组、C肽组,经腹腔埋入微渗泵用药。以同龄正常Wistar大鼠为正常组。用药前及用药后每4周检测各组大鼠血糖及24 h尿白蛋白。用药12周后,免疫组织化学染色观察大鼠肾小管间质转化生长因子β1(TGF-β1)表达;新鲜肾小管间质组织匀浆WST-1法检测超氧化物歧化酶(SOD)活性,TBA法检测丙二醛(MDA)含量,Real-time PCR检测蛋白激酶A m RNA的表达。结果:与正常组对比,对照组大鼠血糖及24 h尿白蛋白升高,肾小管间质TGF-β1表达增加、SOD活性降低、MDA含量升高、蛋白激酶A m RNA表达下调;经C肽干预后,大鼠血糖无明显变化,24 h尿白蛋白升高减缓,肾小管间质TGF-β1表达减少、SOD活性升高、MDA含量降低、蛋白激酶A m RNA表达上调。结论:C肽通过激活蛋白激酶A途径减轻糖尿病肾病大鼠肾小管间质的氧化应激反应,改善肾小管间质纤维化,减轻蛋白尿。

Objective To investigate the effect of C peptide on tubulointerstitial oxidative stress injury in rats with diabetic nephropathy （DN） induced by streptozotocin （STZ）. Methods Wistar rats with DN induced by STZ were randomly divided into control group and C peptide, group. All rats were treated via intraperitoneal microosmotic pump. Normal Wistar rats at the same age were used as the normal group. Blood glucose and24 h urinary albumin were measured before treatment and every 4 weeks during treatment period. After 12 weeks of treatment, the expression of transforming growth factor- β1 （TGF- β1） in renal tubulointerstitium was detected by immunohistochemical staining. Fresh tubulointerstitial tissue homogenate was harvested and the activity of superoxide dismutase （SOD） was detected in WST- 1 method, the content of malondialdehyde （MDA） was detected in TBA method, and the expression of protein kinase A （PKA） mRNA was detected by Real-time PCR. Results Levels of blood glucose, 24 h urinary albumin, MDA content and the expression of TGF- β1 were higher in the control group than those in the normal group, while SOD activity decreased and PKA mRNA was downregulated. C peptide treatment did not change blood glucose level but slowed down the increasing of 24 h urinary albumin, reduced the tubulointerstitial TGF-β1 expression and MDA content, increased the SOD activity and upregulated the PKA mRNA expression. Conclusions C-peptide can decrease the tubulointerstitial oxidative stress in DN rats by activating PKA pathway and then improve tubulointerstitial fibrosis and attenuate proteinuria.