School of Environmental Science and Engineering, Shandong University, Jinan 250100, China; School of Municipal and Environmental Engineering, Shandong Jianzhu University, Jinan 250101, China.
School of Environmental Science and Engineering, Shandong University, Jinan 250100, China.
Ecotoxicol Environ Saf. 2018 Apr 30;151:161-169. doi: 10.1016/j.ecoenv.2017.12.062. Epub 2018 Jan 30.
As the producer of reactive oxygen species (ROS), both lead (Pb) and paraquat (PQ) can generate serious oxidative stress in target organs which result in irreversible toxic effects on organisms. They can disturb the normal catalytic activities of many enzymes by means of different toxicity mechanism. The changed responses of enzymes are frequently used as the biomarkers for indicating the relationship between toxicological effects and exposure levels. In this work, goldfish was exposed to a series of test groups containing lead and paraquat in the range of 0.05-10mg/L, respectively. Four hepatic enzyme activities, including 7-ethoxyresorufinO-deethylase (EROD), 7-benzyloxy-4-trifluoromethyl-coumarin-O-debenzyloxylase (BFCOD), glutathione S-transferase (GST) and UDP-glucuronosyltransferase (UGT) were determined after 1, 7, 14, 28 days exposure. The results showed that the activities of EROD and BFCOD in fish were significantly inhibited in response to paraquat at all exposure levels during the whole experiment. Similarly, the inhibitory effects of lead exposure on BFCOD activity were found in our study, while different responses of lead on EROD were observed. There were no significant differences on EROD activity under lower concentrations of lead (less than 0.1mg/L) before 14 days until an obvious increase was occurred for the 0.5mg/L lead treatment group at day 14. Furthermore, lead showed stronger inhibition on GST activity than paraquat when the concentrations of the two toxicants were more than 0.5mg/L. However, the similar dose and time-dependent manners of UGT activity were found under lead and paraquat exposure. Our results indicated that higher exposure levels and longer accumulations caused inhibitory effects on the four enzymes regardless of lead or paraquat stress. In addition, the responses of phase I enzymes were more sensitive than that of phase II enzymes and they may be served as the acceptable biomarkers for evaluating the toxicity effects of both lead and paraquat.
作为活性氧（ROS）的产生者，铅（Pb）和百草枯（PQ）均可在靶器官中产生严重的氧化应激，从而对生物体造成不可逆转的毒性影响。它们可以通过不同的毒性机制干扰许多酶的正常催化活性。酶的变化反应经常被用作指示毒理学效应与暴露水平之间关系的生物标志物。在这项工作中，金鱼分别暴露于 0.05-10mg/L 范围内的一系列含铅和百草枯的实验组中。在整个实验过程中，在所有暴露水平下，鱼体内的四种肝酶活性（包括 7-乙氧基Resorufin-O-去乙基酶（EROD）、7-苄氧基-4-三氟甲基香豆素-O-去苄氧酶（BFCOD）、谷胱甘肽 S-转移酶（GST）和 UDP-葡糖醛酸基转移酶（UGT））在接触百草枯后均受到显著抑制。同样，在本研究中也发现了铅暴露对 BFCOD 活性的抑制作用，而对 EROD 的抑制作用则不同。在 14 天之前，在较低浓度的铅（小于 0.1mg/L）下，EROD 活性没有明显差异，直到 0.5mg/L 铅处理组在第 14 天出现明显增加。此外，当两种毒物的浓度超过 0.5mg/L 时，铅对 GST 活性的抑制作用强于百草枯。然而，在铅和百草枯暴露下，UGT 活性表现出相似的剂量和时间依赖性。我们的结果表明，无论受到铅还是百草枯的压力，较高的暴露水平和较长的积累都会对这四种酶产生抑制作用。此外，I 相酶的反应比 II 相酶更敏感，它们可以作为评估铅和百草枯毒性效应的可接受生物标志物。
