番茄红素缓解AFB1致肉鸡肝脏及线粒体损伤的作用机制研究

Mycotoxins, especially aflatoxin B1 (AFB1), are prevalent in animal production and very detrimental to animal and human health. AFB1, which is hepatotoxic, is metabolized by cytochrome P450 (CYP450) enzymes accompanied by reactive oxygen species (ROS) production. The oxidative stress and mitochondrial dysfunction induced by ROS are important hepatotoxicity effects of AFB1. Lycopene (LYC), which is one of the most potent antioxidants in natural plants, can alleviate toxicity effects through regulating phase I and phase II metabolism and Nrf2 pathway. However, whether LYC can attenuate AFB1 induced liver and mitochondrial injury in poultry and the mechanism are unclear. At first, this study analyzes the oxidative damage and antioxidant capacity of liver and mitochondria, the activities of respiratory chain complex, mitochondrial membrane potential and adenosine level, to evaluate the effects of LYC on redox status and mitochondrial function of liver in AFB1-challenged broilers. Then, the research explores the mRNA expressions levels of CYP450 enzymes and Nrf2-mediated phase II enzyme systems, as well as the of mitochondrial pathway in liver, to reveal the regulating mechanism of LYC in AFB1 metabolism and detoxification enzymes and key factors of mitochondrial function and biosynthesis. The results will provide theoretical basis for botanical feed additive in alleviating mycotoxin-induced damages.

以黄曲霉毒素B1（AFB1）为代表的霉菌毒素在动物生产中普遍存在，严重威胁动物和人类健康。AFB1是肝毒性化学物质，在细胞色素P450（CYP450）酶的作用下产生活性氧自由基（ROS）诱导氧化应激和线粒体损伤是其产生毒性危害的重要途径。番茄红素（LYC）是天然强抗氧化剂，能够调节I相、II相代谢和Nrf2信号通路缓解毒性物质危害。然而LYC能否缓解AFB1致肉鸡肝脏及线粒体损伤及其具体机制尚不明确。本项目通过分析肝脏及线粒体氧化损伤和抗氧化能力、线粒体呼吸链复合物的活性、膜电位、腺苷酸水平，探索LYC对AFB1应激肉鸡肝脏氧化还原状态和线粒体功能的影响；通过研究肝脏中CYP450酶、Nrf2介导的II相酶和线粒体途径关键因子的表达水平，揭示LYC对AFB1代谢与解毒相关酶、线粒体功能和生物合成关键因子的调节机制，为植物源添加剂缓解霉菌毒素应激损伤提供理论依据。

以黄曲霉毒素B1（AFB1）为代表的霉菌毒素在动物生产中普遍存在，严重威胁动物和人类健康。AFB1是肝毒性化学物质，在细胞色素P450（CYP450）酶的作用下产生活性氧自由基（ROS）诱导氧化应激和线粒体损伤是其产生毒性危害的重要途径。番茄红素（LYC）是天然植物源抗氧化剂，能够调节I相、II相代谢和Nrf2信号通路缓解毒性物质危害。然而LYC能否缓解AFB1致肉鸡肝脏及线粒体损伤及其具体机制尚不明确。本项目研究了LYC对饲喂AFB1污染饲粮的肉鸡肝脏及线粒体损伤的缓解作用。结果显示，与对照组相比，AFB1暴露的鸡生长性能下降，肝脏受到损伤、并产生氧化应激。LYC可缓解AFB1诱导的生长抑制，降低肝脏CYP450同工酶活性和mRNA表达，减少氧化损伤产物，改善还原性谷胱甘肽(GSH)依赖的解毒系统和抗氧化系统；LYC提高了AFB1暴露肉鸡Nrf2及其靶基因(包括谷胱甘肽-s-转移酶、谷胱甘肽合成相关酶和抗氧化酶)的表达水平。进一步研究发现，AFB1暴露可引起肉鸡肝脏线粒体谷胱甘肽(mGSH)浓度和谷胱甘肽过氧化物酶(GSH-Px)、锰超氧化物歧化酶(MnSOD)、硫氧还蛋白还原酶活性降低，过氧化氢(H2O2)和ROS浓度升高，线粒体肿胀度增加，ATP浓度降低。而且AFB1降低了线粒体电子转移链(ETC)复合物的活性，下调了肝脏MnSOD、硫氧还蛋白2、硫氧还蛋白还原酶、过氧化物酶-3、过氧化物酶体增殖物激活受体γ共激活因子1α、核呼吸因子1和线粒体转录因子A的表达水平。而LYC提高了AFB1暴露的肉鸡肝脏线粒体 mGSH浓度以及GSH-Px和MnSOD活性，降低了H2O2和ROS浓度，增加了线粒体ETC复合物活性，上调了线粒体抗氧化和生物合成相关因子表达水平。因此，LYC可能通过抑制CYP450同工酶和改善Nrf2介导的解毒和抗氧化系统来减轻AFB1诱导的肝损伤，而且对AFB1诱导的肉仔鸡肝脏线粒体氧化损伤和功能障碍具有保护作用。本项目研究结果有助于明晰LYC对AFB1应激肉鸡肝脏氧化还原状态和线粒体功能的影响，揭示LYC对AFB1代谢与解毒相关酶、线粒体功能和生物合成关键因子的调节机制，为植物源添加剂缓解霉菌毒素应激损伤提供理论依据。