依那普利对单侧尿路梗阻大鼠肾组织Smad2/3活性的影响

Effect of Enalapril on the Activity of TGF-β Signal Protein Smad2/3 in the Kidney After Unilateral Ureteral Obstruction in Rats

目的：研究血管紧张素转换酶抑制剂（ACEI）依那普利对单侧尿路梗阻大鼠肾组织Smad2／3信号蛋白活性的影响。方法：采用单侧输尿管结扎（UUO）模型，治疗组从造模前24h至造模后28d以依那普利10 mg·kg^-1·d^-1灌胃，另设假手术组作正常对照。分别于造模后1，3，7，14，21和28d取肾组织，应用免疫组化法检测肾组织TGF-β1、磷酸化Smad2／3和α—SMA表达。结果：正常大鼠肾组织具有基础的TGF-β1（4.32±1.72）％和磷酸化Smad2／3（19．31±5.37）个／mm^2的表达，α—SMA只表达于血管平滑肌，肾小管-间质无表达。UUO术后1d，TGF-β1的表达无明显增加（5．15±2．08）％，第3d明显增加（13．55±6．33）％，第7d达高峰（26．78±8．77）％，此后表达减少；UUO术后3d，磷酸化Smad2／3的表达明显增加（67．95±13．87）个／mm^2，并持续增加到第7d（150．61±27．34）个／mm^2，此后表达减少；而UUO术后3d，肾组织α-SMA表达亦明显升高（5．58±1．23）％，第7d达到高峰（13．43±3．32）％，14d表达开始下调。依那普利治疗可以明显抑制肾组织TGF-β1信号蛋白Smad2／3活性（降低39％～55％，P〈0．01），显著下调肾组织α—SMA的表达（降低44％～58％，P〈0．01），减轻肾间质纤维化。结论：依那普利可显著抑制梗阻肾肾组织α—SMA的表达，减轻梗阻肾间质纤维化，这一作用可能与其抑制肾组织TGF-β1信号蛋白Smad2／3的活性有关．

Objective：To investigate the effect of ACEI enalapril on the activity of TGF-β signal protein Smad2/3 in the obstructed kidney after unilateral ureteral obstruction（UUO） of rats. Methods： The UUO model was induced by ligating the left ureter. Rats were divided into normal control （sham operation）, model and treatment groups（enalapril 10 mg·kg^-1 ·d^-1 by gastric gavage） from 24 h before the obstruction to day 28 after the induction of UUO. Rats were sacrificed at 1,3,7,14,21, and 28days after UUO was initiated. Sections of renal tissue were stained with HE, PAS and Masson, which were used for histological and morphometric studies of the pathological change of the obstructed kidney. Immunohistochemical staining was performed to investigate the expression of TGF-β1 , phosphorylated Smad2/3 and interstitial α- smooth muscle actin （α- SMA） in the obstructed kidney. Results：A basal TGF- β and pbosphorylated Smad2/3 expression was detectable in normal kidney; α - SMA was only detected in vascular smooth muscle. Significant upregulation of TGF - β was found in tubulointerstitium of both cortex and medulla at day 3 （3.1 fold vs control, P〈0.05） when interstitial volume start to increase. The highest expression of TGF -β1 was detected at day 7 （6.2 folds vs control, P 〈 0.01 ）. Phosphrylated Smad2/3, mainly detected in the nucleus of tubular cells, was also markedly upregulated at day 3 （3.5 fold increase vs control, P 〈 0.05 ）and day 7 （7.8 folds vs control, P 〈 0.01 ）. The expression of interstitial α - SMA in both cortex and medulla was evident at day 3 （3.8 fold increase vs control,P〈0.05） and reached the peak by day 7 （9.2 folds vs control, P〈0.01）. Interestingly, blockade of Ang Ⅱ with enalapril significantly suppressed the expression of phosphrylated Smad2/3 （reduced by 39% -55%, P〈0.01）. Similary, inhibition of Ang Ⅱ resulted in significant suppression of α- SMA expression in the obstructed kidney （reduced by 44 % - 58 %, P 〈 0.01 ）. Conclusion： Enalapril significantly alleviates renal tubulointerstitial fibrosis by suppressing the expression of α- SMA in the obstructed kidney, which may associated with the inhibition of Smad2/3 activity.