龙胆苦苷通过抑制TLR4/MyD88/NF-κB信号通路减轻小鼠急性肝损伤的作用

Protective Effect of Gentiopicroside Against Liver Injury in Mice via TLR4/MyD88/NF-κB Signaling Pathway

目的:探究龙胆苦苷(GPS)对四氯化碳(CCl4)诱导的急性肝损伤小鼠模型是否有保肝疗效及其对Toll样受体4(TLR4)/髓样分化因子88(MyD88)/核转录因子-κB(NF-κB)信号通路的影响。方法:将60只小鼠随机分为6组,每组10只,分别为正常组、模型组、水飞蓟素(150 mg·kg^(-1))组及GPS高、中、低剂量组(200,100,50 mg·kg^(-1))。给药组的小鼠按10 mL·kg^(-1)灌胃处理,正常组和模型组灌胃相同量的蒸馏水,每天1次,连续灌胃给药10 d后,除正常组腹腔注射花生油(10 mL·kg^(-1)),其余各组腹腔注射0.12%CCl4花生油(10 mL·kg^(-1))溶液建立小鼠急性肝损伤模型。腹腔注射后禁食16 h,摘除小鼠眼球取血,收集肝脏组织。苏木素-伊红(HE)染色观察肝组织病理学改变。生化法检测各组小鼠血清中丙氨酸氨基转移酶(ALT),天门冬氨酸氨基转移酶(AST),总胆红素(TBIL),碱性磷酸酶(ALP),总超氧化物歧化酶(T-SOD),γ-谷氨酰转肽酶(γ-GT)的水平,肝组织中丙二醛(MDA),谷胱甘肽过氧化物酶(GSH-Px)的水平;酶联免疫吸附法(ELISA)检测小鼠肝脏组织中的肿瘤坏死因子-α(TNF-α),白细胞介素-1β(IL^(-1)β),白细胞介素-6(IL-6)含量。蛋白免疫印迹法(Western blot)测定肝脏组织中TLR4,MyD88,NF-κB蛋白表达情况;免疫组化检测磷酸化NF-κB(p-NF-κB)的表达。结果:与正常组比较,模型组小鼠的ALT,AST,ALP,TBIL,γ-GT及MDA水平显著升高(P<0.01),T-SOD,GSH-Px活性显著降低(P<0.01);与模型组比较,GPS中、高剂量组小鼠的ALT,AST,ALP,TBIL,γ-GT及MDA水平降低(P<0.05,P<0.01),T-SOD、GSH-Px活性明显上升(P<0.05,P<0.01);与正常组比较,模型组小鼠肝组织中TNF-α,IL^(-1)β,IL-6含量显著升高(P<0.01),TLR4,MyD88,p-NF-κB蛋白表达显著上升(P<0.01);与模型组比较,GPS中、高剂量组小鼠肝组织中TNF-α,IL^(-1)β,IL-6含量明显降低(P<0.05,P<0.01),TLR4,MyD88,p-NF-κB蛋白表达明显下调(P<0.05,P<0.01)。结论:GPS对CCl4引起的急性肝损伤小鼠具有一定的保肝效果,其作用机制可能与调控TLR4/MyD88/NF-κB信号通路及减弱氧化应激反应相关。

Objective: To explore the mechanism of gentiopicroside(GPS)in preventing acute liver injury induced by carbon tetrachloride(CCl4)in mice and its effect on the Toll-like receptor 4(TLR4)/myeloid differentiation factor 88(MyD88)/nuclear factor-κB(NF-κB)signaling pathway. Method: Sixty mice were randomly divided into a normal control group,a model group,a silymarin group(150 mg·kg(-1)),and high-(200 mg·kg(-1)),medium-(100 mg·kg(-1)),and low-dose(50 mg·kg(-1))GPS groups,with 10 in each group. The mice in the groups with drug intervention were administered correspondingly by gavage at 10 mL·kg(-1),and those in the normal control group and the model group receive an equal volume of distilled water,once per day. Ten days after administration,mice in the normal control group were subjected to the intraperitoneal injection of peanut oil(10 mL·kg(-1))and those in other groups were injected with peanut oil(10 mL·kg(-1))containing 0.12%CCl4 for the induction of acute liver injury model. After fasting for 16 hours,blood was collected from eyeballs and liver tissues were collected. Hematoxylin-eosin(HE)staining was used to observe the pathological changes of liver tissues. The content or activities of alanine aminotransferase(ALT),aspartate aminotransferase(AST),total bilirubin(TBIL),alkaline phosphatase(ALP),total superoxide dismutase(T-SOD),and γ-glutamyl transpeptidase(γ-GT)in the serum,malondialdehyde(MDA)and glutathione peroxidase(GSH-Px)in liver tissues were determined by biochemistry techniques. The levels of tumor necrosis factor-α(TNF-α),interleukin-1β(IL^(-1)β),and interleukin-6(IL-6)in liver tissues were measured by enzyme-linked immunosorbent assay(ELISA). Western blot was used to detect the protein expression of TLR4,MyD88,and NF-κB in liver tissues.The expression of phosphorylated NF-κB(p-NF-κB) was detected by immunohistochemistry. Result:Compared with the normal control group,the model group showed increased levels of ALT,AST,ALP,TBIL,γ-GT,and MDA(P<0.01),and blunted activities of T-SOD and GSH-Px(P<0.01). Compared with the model group,the high-and medium-dose GPS groups exhibited declining levels of ALT,AST,ALP,TBIL,γ-GT,and MDA(P<0.05,P<0.01)and potentiated T-SOD and GSH-Px activities(P<0.05,P<0.01). Compared with the normal control group,the model group displayed elevated levels of TNF-α,IL^(-1)β,and IL-6 in liver tissues(P<0.01)and increased protein expression of TLR4,MyD88,and p-NF-κB(P<0.01). Compared with the model group,the high-and medium-dose GPS groups showed decreased TNF-α,IL^(-1)β,and IL-6 content in liver tissues(P<0.05,P<0.01)and dwindled TLR4,MyD88,and p-NF-κB protein expression(P<0.05,P<0.01). Conclusion: GPS possesses a protective effect on mice with acute liver injury induced by CCl4,and its mechanism of action may be related to the regulation of TLR4/MyD88/NF-κB signaling pathway and inhibition of oxidative stress.