甘草酸二胺对输尿管梗阻大鼠肾间质纤维化的治疗作用及机制

Effect of Glycyrrhizin Acid on Expression of Renal Interstitial Fibrosis and its Mechanism in Rats with Unilateral Ureteral Obstruction

目的:探讨甘草酸二胺对肾间质纤维化的作用及其机制。方法:以Wistar大鼠单侧输尿管梗阻(UUO)为模型,在不同的时间点(7d、14d、28d)观察梗阻侧肾间质纤维化指数;致纤维化的转化生长因子β1(TGF-β1)的表达情况;肾皮质中与肾脏纤维化相关的Smurf2、Smad7信号蛋白等的mRNA及蛋白表达。结果:(1)随着梗阻时间的延长,肾间质纤维化程度逐渐加重,Smurf2基因和蛋白质明显上调,呈时间依赖性(P<0.01);Smad7蛋白呈时间依赖性下调(P<0.01),Smad7基因在各个时间点无明显变化;TGF-β1基因在UUO后第7d达高峰,此后逐渐下降,但仍然高于假手术组(P<0.01)。(2)甘草酸能改善UUO所致的肾间质纤维化程度(P<0.01),下调肾脏组织TGF-β1基因的表达(P<0.01);减少Smurf2基因和蛋白质的表达,同时上调TGF-β1信号传导中抑制性因子Smad7的表达(P<0.01)。结论:甘草酸二胺能保护UUO所致的肾间质纤维化损伤。其可能的作用机制为减少Smurf2核酸和蛋白质的表达,增加抗纤维化作用的Smad7蛋白表达;减少TGF-β1表达,阻止TGF-β信号传导,从而阻断肾间质的纤维化。

Objective：To investigate the effects of glycyrrhizin acid（GA） on renal interstitial fibrosis and its mechanism. Methods：Adult male Wistar rats were randomly divided into three groups： Sham operation group（Sham） ;UUO group, undergoing unilateral left ureteral obstruction; UUO and GA treatment （20 mg·kg^-1·d^-1 group（UUO ＋ GA）. Each group was subdivided into sub -groups（6 for each）according to different treating time as 7 days, 14 days and 28 days,and their left kidneys were taken out at the respective time to undergo light microscopy by Masson staining to observe the renal interstitial fibrosis index. At the different time point, Reverse transcription- polymerase chain reaction （RT- PCR） was used to detect the mRNA expression of Smurf2, Smad7and TGF- !31 ;Western blotting methods was used to detect the protein expression of Smurf2 and SmadT. Results： Twenty - eight days after the intervention, the fibrosis index of the UUO group were significantly increased and the fibrosis index values of UUO＋ GA groups were significantly lower than that of the UUO group （both P 〈 0.01 ）with a significant diference between the two groups. Smurf2 mRNA and protein were increased in the UUO group in a time - dependent manner, however the Smurf2 mRNA and protein expression of the UUO ＋ GA group was significantly reduced compared with that of the UUO group （all P〈 0.01 ）. There was no significant difference of Smad7mRNA between the three groups;Significant decreases of Smad7 protein were noted in UUO kidneys compared with sham - operation group. TGF - 13l mRNA expression peaked at the 7th day after UUO and then decreased gradually,but compared with the sham operation group, its expression is higher on days 7, 14 and 28 day respectively. Conclusion： GA inhibits the renal interstitial fibrosis lesion, downregulates the expression of Smurf2 and TGF- 131, and up - regulate the Smad7 expression, thus blocking renal fibrosis.