替米沙坦降低转化生长因子β1／Smads在高盐诱导肾脏纤维化中的表达

Telmisartan decreased the expressions of transforming growth factor-β_1/ Smads in renal fibrosis of Wistar rats induced by high-salt diet

目的探讨转化生长因子β1(TGF-β1)/Smads表达在高盐饮食诱导肾脏纤维化中的作用以及替米沙坦的干预效应。方法雄性Wistar大鼠49只,分为对照组(n=13,0.5%正常盐)、高盐组(n=24,8%高盐)、干预组[n=12,8%高盐+替米沙坦(2～40)mg/(kg·d)]。24周时利用尾动脉测压仪监测尾动脉收缩压;测压后代谢笼收集24h尿液;Masson染色观察肾脏纤维化;生化方法测定24h尿微量白蛋白、血尿肌酐及24h尿钠排出量;real-timePCR法检测肾脏皮质区TGF-β1、Smad2、Smad3、Smad7的mRNA表达,Westernblot法检测皮质区α平滑肌肌动蛋白(α-SMA)、TGF-β1、磷酸化Smad2/3(p-Smad2/3)、Smad7的蛋白表达。结果与对照组相比,高盐组的大鼠血压升高[(152.9±32.1)比(119.5±7.2)mmHg,P<0.05],肾小球及肾间质的纤维化指数增高(22.51±2.40比14.13±1.05,25.89±4.18比13.76±1.79,均P<0.01),24h尿微量白蛋白和尿钠排出量增高,内生肌酐清除率(Ccr)降低;肾脏皮质区的TGF-β1、Smad2、Smad3、Smad7mRNA表达升高,α-SMA、TGF-β1、p-Smad2/3、Smad7蛋白表达增高。替米沙坦干预后,大鼠尾动脉收缩压较高盐组降低[(127.8±4.3)比(152.9±32.1)mmHg,P<0.05],肾小球及肾间质的纤维化指数降低(14.50±1.35比22.51±2.40,14.91±1.77比25.89±4.18,均P<0.01),24h尿微量白蛋白排出量下降,24h尿钠排出量和Ccr差异无统计学意义(P>0.05),上述各基因和蛋白表达也降低(均P<0.05)。结论 TGF-β1/Smads表达异常参与高盐诱导肾脏纤维化的机制;替米沙坦可能通过阻断血管紧张素Ⅱ1型受体降低TGF-β1/Smads表达,减轻肾脏损伤。

Objective To study the role of transforming growth factor-β1 （TGF-β1）/Smads expression in renal fibro- sis induced by high-salt diet in Wistar rats and the intervention effect of telmisartan. Methods Forty-nine male Wistar rats were randomly divided into three groups： control group In= β1, regular salt （0.5%）], high salt group In= 24, high salt （ 8% ） ], and intervention group [n = 12, high salt （ 8% ） ＋ telmisartan： 2 - 40 mg/（ kg · d） ]. The systolic blood pressure of the tail artery was measured by the tail-cuff method at the 24th week. The 24 h urine was collected by metabolic cages after the manometry and the renal fibrosis was observed by Masson staining. 24 h urinary microalbumin excretion, 24 h urinary sodium excretion, and the levels of serum creatinine and urinary creati- nine were determined by biochemical methods. In addition, the technique of real time PCR was used to detect the mRNA expression of TGF-β1, Slnad2, Smad3, and Smad7. Western blot was employed to determine the protein expression of a-smooth muscular actin （a SMA）, TGF-β1 , phosphorylated Smad2/3（p-Smad2/3） , and Smad7 in the renal cortex. Results Compared with those of the control group, the blood pressure [（152.9±32.1） vs （119.5±7.2）ram Hg, P〈0.05], fibrosis index of glomerular [（22.51±2.40） vs （14.13±1.05）, P〈0.01] and interstiti- urn[（25. 894±4. 18） vs （13.76±1.79）, P〈0.01], and 24 h urinary microalbumin and urinary sodium excretion were increased in hte high salt group, while the endogenous creatinine clearance rate（Ccr） was decreased. And inthe high salt group, the mRNA expressions of TGF-β1, Smad2, Smad3, Smad7 and the protein expressions of a-SMA, TGF-β1 , p-Smad2/3, Smad7 were all increased in the renal cortex. After the intervention of telmisartan, the systolic blood pressure [（127.8±4.3） vs （152.9±32.1）mm Hg, P〈0.05], fibrosis index of the glomerular [（14.50±1.35） vs （22.51±2.40）, P〈0.01] and interstitium[（14.91±1.77） vs （25.89±4.18）, P〈0.01], and 24h urinary microalbumin excretion were reduced compared with those of the high salt group, while the 24h urinary sodium excretion and Ccr didn＇t have statistically significant change（P〉0.05 ）, and the expressions of the above genes and proteins were also significantly decreased （all P〈0.05）. Conclusion Abnormal expressions of TGF-β1/ Smads were involved in the mechanism of high-salt-induced renal fibrosis. Telmisartan may alleviated kidney dam- age via reducing TGF-β1/Smads expressions which was mediated by blocking AT1 receptor.