氯沙坦对糖尿病大鼠肾小管间质P38 MAPK表达的影响

Effects of Losartan on the Expression of Phosphorylated P38 Mitogen-activated Protein Kinase in Renal Tubulointerstitium in Experimental Diabetic Rats

【目的】探讨P38丝裂原活化的蛋白激酶(P38MAPK)与糖尿病肾病(DN)肾小管间质病变的关系,及氯沙坦对其的影响。【方法】雄性Wistar大鼠,随机分为正常对照组和模型组,后者经STZ诱导糖尿病模型成功后再随机分为糖尿病模型组和氯沙坦干预组。8周后检测各组大鼠24 h尿蛋白、血肌酐;留取肾组织行HE和MASSON染色,观察肾小管间质损伤指数、肾间质胶原面积;免疫组化检测肾小管间质磷酸化P38MAPK以及TGFβ1表达,并做半定量分析。【结果】①与对照组相比,糖尿病模型组大鼠尿蛋白排泄量、肾小管间质损伤指数和肾间质胶原面积明显增加(P<0.01);②糖尿病组大鼠肾小管间质磷酸化P38MAPK、TGFβ1表达均显著高于对照组(P<0.01);③氯沙坦组尿蛋白排泄量、肾小管间质损伤程度较糖尿病组减轻,肾小管间质磷酸化P38MAPK、TGFβ1表达较糖尿病组显著下调(P<0.01)。【结论】糖尿病肾病小管间质病变的病理过程中存在P38MAPK的活化;氯沙坦可阻抑糖尿病大鼠肾小管间质P38MAPK活化,下调TGFβ1表达而发挥肾脏保护作用。

[Objective]To investigate whether p38 MAPK is associated with the development of tubulointerstitial lesions and the effects of Losartan on the expression of the phosphorylated p38 MAPK in renal tubulointerstitium in experimental diabetic rats. [Methods]Male Wistar rats were randomly divided into two groups： control and diabetic group. Diabetes was induced by intraperitoneal injection of STZ. Diabetic group was divided into diabetic and Losartan treatment group. Eight weeks later, samples were collected to determine urinary protein excreted in 24 hours and serum creatinine. A portion of renal tissue was analyzed with hematoxylin ＆ eosin stain and Masson stain. The extent of tubulointerstitial injury was evaluated and graded, levels of phosphorylated p38 and transforming growth factor-betal（TGFβ1） were assessed by Immunohistochemistry in rats. Computer image-pattern analysis system was used to analyze the expression of P-P38 MAPK and TGF-β1 in renal tubulointerstitium. [Resuhs]（1）The amount of urinary protein excreted in 24 hours and the tubulointerstitial lesions and the accumulation of extracellular matrix protein were significantly greater in diabetic rats than in control rats （ P〈0. 01）（2）Expression of P-p38 MAPK in diabetic tubulointerstitium in diabetic rats was higher than in the controls, the same as the expression of TGF-betal （ P〈0.01）. （3）After Losartan treatment, urinary protein excreted in 24 hours and the tubulointerstitium lesions and the accumulation of extracellular matrix protein was ameliorated, and the expressions of P-P38 MAPK as well as TGF-betal were markedly decreased compared with diabetic group（ P〈0.01）. [Conclusion]These results suggest p38MAPK phosphorylation and the up-regulation of TGF betal contribute to the development of tubulointerstitial lesions in diabetic nephropathy; inhibition of tubulointerstitial p38 MAPK activation and the expression of TGF betal may be responsed for the renal protective effects of Losartan in experimental diabetic nephropathy rats.