甘草酸单铵保护利福平致大鼠肝损伤的机制初探

目的: 本文基于肝细胞膜转运体多药耐药相关蛋白2(multidrug resistance protein 2, Mrp2)和Na⁺-牛磺酸钠共转运体(sodium taurocholate cotransporting polypeptide, Ntcp),初步探究甘草酸单铵(monoammonium glycyrrhizinate,MAG)对利福平(rifampicin,RIF)致大鼠肝损伤的保护作用及机制。方法: Wistar雄性大鼠随机分为3组:对照组(control组):灌胃等容量的生理盐水;RIF肝损伤组(RIF组):灌胃RIF 60 mg·kg^-1·d^-1;MAG治疗组(MAG+RIF组):灌胃MAG 45 mg·kg^-1·d^-1 3 h后灌胃RIF 60 mg·kg^-1·d^-1。给药第7,14,21天时,各组分别随机取5只大鼠分离血清测定生化指标;取肝组织做病理切片,观察肝脏组织病理学变化并进行肝组织学活动指数(HAI)评分;采用 Western blotting法检测肝组织Mrp2和Ntcp蛋白表达量。结果: 与对照组相比,RIF组给药7,14,21 d时,其部分血清生化指标呈明显上升趋势,肝脏病理学HAI分值显著增加(P<0.01);MAG+RIF组血清生化指标与对照组之间无显著差异,与RIF组相比其HAI评分显著降低(P<0.05)。给药7,14,21 d时,RIF组较对照组Mrp2的表达均显著升高(P<0.05),而MAG+RIF组Mrp2的表达均显著低于RIF组(P<0.05)。给药期间,各组Ntcp的表达均无显著差异(P>0.05)。结论: 利福平肝损伤机制可能与其上调Mrp2有关,MAG可保护利福平诱导的肝损伤,且其保肝作用可能与其下调Mrp2有关。

Primary investigation on protective effects of monoammonium glycyrrhizinate against hepatic injuries induced by rifampicin in rats

OBJECTIVE To investigate protective effects and mechanism of monoammonium glycyrrhizinate (MAG) against rifampicin (RIF) induced hepatotoxicity based on the hepatobiliary membrane transporters including multidrug resistance protein 2 (Mrp2) and sodium taurocholate cotransporting polypeptide (Ntcp).METHODS Male Wistar rats were randomly divided into three groups: control group, RIF group, RIF+MAG group. Rats were orally administered with RIF (60 mg·kg^-1·d^-1) in RIF group, saline in control group. Rats were orally administrated with MAG (45 mg·kg^-1·d^-1) 3 h before RIF (60 mg·kg^-1·d^-1) in RIF+MAG group. Drugs were given to rats once a day for successive 21 days. To evaluate dynamic effects of drugs, rats in each group were sacrificed respectively at 7, 14 and 21 days after drug administration. At each time point, 5 rats in each group were randomly selected, fasted for 6 h and anesthetized with ether. Blood samples were collected by abdominal aortic puncture, and serum was obtained for analysis of ALT, AST, TBIL, DBIL, IBIL and TBA. Liver tissues were harvested immediately, a part of tissues was fixed in 10% formaldehyde for histological analysis, the remaining was frozen with liquid nitrogen and stored at -80℃ for Western blotting analysis to detect expression of Mrp2 and Ntcp.RESULTS Compared to control group, levels of serum biochemical indicators were significantly elevated 7, 14, and 21 days after RIF administration, and HAI scores were also markedly increased (P<0.05), suggesting that hepatotoxicity was induced by RIF. Compared to RIF group, RIF+MAG treatment significantly and dose-dependently reduced AST, ALT, TBIL and TBA levels as well as HAI scores 7, 14 and 21 days after drug administration, respectively. Compared to control group, expression of Mrp2 was significantly increased (P<0.05) in RIF-treated group, while RIF+MAG treatment significantly reduced expression of Mrp2 in RIF-treated rats (P<0.05). No significant difference of Ntcp expression was found (P>0.05). CONCLUSION RIF induced liver injuries have close correlation with up-regulated expression of Mrp2. MAG shows protective effects to liver in rats with liver injuries induced by RIF, and the underlying mechanism may be related with down-regulation of Mrp2 expression.