目的 基于c-jun N末端激酶(c-Jun N-terminal kinase,JNK)信号通路探讨儿茶素对对乙酰氨基酚(acetaminophen,APAP)诱导肝损伤的作用及机制。方法 ICR小鼠随机分为对照组、模型组以及儿茶素(50、100 mg/kg)组,小鼠连续3 d ig儿茶素,末次给予儿茶素1 h后ip APAP(400 mg/kg),6 h后采用苏木素-伊红(HE)染色评估小鼠肝脏组织病变,检测血清中丙氨酸氨基转移酶(alanine aminotransferase,ALT)、天冬氨酸氨基转移酶(aspartate aminotransferase,AST)活性及肝脏中谷胱甘肽(glutathione,GSH)水平、超氧化物歧化酶(superoxide dismutase,SOD)活性;考察儿茶素对细胞色素P450(cytochrome P450,CYP450)代谢酶活性的影响。人正常肝细胞L02给予40、80 μmol/L儿茶素,15 min后给予15 mmol/L APAP孵育6 h,检测活性氧(reactive oxygen species,ROS)水平、线粒体膜电位变化、线粒体呼吸链复合物I活性、三磷酸腺苷(adenosine triphosphate,ATP)含量、胞质B淋巴细胞瘤-2相关X蛋白(B-cell lymphoma-2 associated X protein,Bax)、第2个线粒体衍生的半胱氨酸蛋白酶激活剂(second mitochondria-derived activator of caspases,Smac)、凋亡诱导因子(apoptosis inducing factor,AIF)蛋白表达以及线粒体动力相关蛋白1(dynamin-related protein 1,Drp1)、线粒体融合蛋白2(mitofusin 2,Mfn2)、Bax蛋白表达和p-JNK、JNK蛋白表达。给予JNK激活剂后,考察儿茶素对APAP诱导的肝细胞损伤作用。结果 儿茶素显著降低APAP诱导的肝损伤小鼠血清中ALT、AST活性(P<0.05、0.01),显著升高肝脏GSH水平和SOD活性(P<0.05、0.01),改善肝脏损伤。儿茶素显著升高APAP处理的L02细胞存活率、线粒体膜电位、呼吸链复合物I活性和ATP水平(P<0.05、0.01),显著降低ROS水平(P<0.05),显著下调线粒体中Drp1、Bax和胞质中Smac、AIF蛋白表达(P<0.05),显著上调线粒体中Mfn2和胞质Bax的蛋白表达(P<0.05),并抑制JNK的磷酸化水平(P<0.05)。给予JNK激活剂后,儿茶素的抗氧化作用和对肝脏的保护作用明显减弱(P<0.05、0.01)。结论 儿茶素通过抑制JNK信号通路减轻线粒体氧化应激,进而拮抗APAP诱导的肝损伤。

Objective To explore the effect and mechanism of catechin on acetaminophen (APAP)-induced liver injury based on c-Jun N-terminal kinase (JNK) signaling pathway. Methods ICR mice were randomly divided into control, model and catechin (50, 100 mg/kg) groups. The mice were given catechin for three consecutive days through intragastric administration, and after the last dose of catechin for 1 h, mice were ip APAP (400 mg/kg). After 6 h, hematoxylin-eosin (HE) staining was used to evaluate liver tissue lesions in mice. The activities of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) in serum, as well as the level of glutathione (GSH) and activity of superoxide dismutase (SOD) in liver were detected. The effect of catechin on activity of cytochrome P450 (CYP450) metabolic enzymes was observed. Normal human liver cells L02 were given 40 and 80 μmol/L catechin, incubated with 15 mmol/L APAP for 6 h after 15 min, reactive oxygen species (ROS) level, changes in mitochondrial membrane potential, mitochondrial respiratory chain complex I activity, adenosine triphosphate (ATP) content, protein expressions of cytoplasmic B-cell lymphoma-2 associated X protein (Bax), second mitochondrial derived activator of caspases (Smac), apoptosis inducing factor (AIF), as well as mitochondrial dynamin-related protein 1 (Drp1), mitofusin 2 (Mfn2), Bax, and p-JNK, JNK were detected. After administering JNK activators, the effect of catechin on APAP-induced liver cell damage was investigated. Results Catechin significantly reduced the activities of ALT and AST in serum of APAP-induced liver injury mice (P<0.05, 0.01), significantly increased GSH level and SOD activity in liver (P<0.05, 0.01), and improved liver injury. Catechin significantly increased the survival rate, mitochondrial membrane potential, mitochondrial respiratory chain complex I activity and ATP level of L02 cells treated with APAP (P<0.05, 0.01), significantly reduced ROS level (P<0.05), significantly downregulated the protein expressions of Drp1, Bax in mitochondria and Smac, AIF in cytoplasm (P<0.05), significantly upregulated the protein expressions of Mfn2 in mitochondria and cytoplasmic Bax (P<0.05), and inhibited the phosphorylation level of JNK (P<0.05). After administering JNK activators, the antioxidant and liver protective effects of catechins were significantly reduced (P<0.05, 0.01). Conclusion Catechin alleviates mitochondrial oxidative stress by inhibiting JNK signaling pathway, thereby antagonizing APAP induced liver injury.

国家自然科学基金资助项目（81960748）；江西省教育厅科技项目（GJJ211640)