Yang Fangxing, Xu Ying, Pan Hongmei, Wu Desheng
State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, People's Republic of China.
Environ Toxicol Chem. 2008 Jan;27(1):220-5. doi: 10.1897/07-108.1.
As the active metabolites of polychlorinated biphenyl (PCBs), hydroxylated polychlorinated biphenyls (OH-PCBs) are found in wildlife and human tissues. They have been proposed as main contributors for endocrine disruption of PCBs in living organisms. In this study, mono-ortho PCB 156 and its hydroxylated metabolites 4'-OH-PCB 159, 4'-OH-PCB 121, and 4'-OH-PCB 72 were selected to investigate the toxic effects on rat hepatoma H4IIE cell line and rat thyroid follicle FRTL-5 cell line at concentrations of 1, 10(2), 10(4) nM. 7-Ethoxyresorufin-O-deethylase (EROD) and 7-pentoxyresorufin-O-dealkylase (PROD) activities were determined with micro-EROD/PROD to indicate cytochrome P4501A1 (CYP1A1) and cytochrome P4502B (CYP2B) induction in the H4IIE cell after exposure for 72 h. To assess thyroid disruption of these compounds, thyroglobulin concentrations also were detected inside FRTL-5 cell with immunocellularchemistry and in its medium with radioimmunoassay after exposure for 24 h. Significant inductions of EROD activity by PCB156 at 10(2) and 10(4) nM (p < 0.05) were observed, but no effects by the three OH-PCBs in H4IIE cell line. 7-Pentoxyresorufin-O-dealkylase activities were induced only by 10(4) nM of PCB156 and the three OH-PCBs (p < 0.05). Meanwhile, significant increases of thyroglobulin concentrations were observed in the medium of FRTL-5 cell exposed to 4'-OH-PCB 121 and 4'-OH-PCB 72 at all of the test concentrations (p < 0.05), but not to the other compounds. The results demonstrated that mono-ortho PCBs mainly could be metabolized to hydroxylated metabolites through CYP1A1 instead of CYP2B. Moreover, after being metabolized, OH-PCBs still sustained the ability to induce PROD activity and did exhibit the disruption on thyroglobulin synthesis/excretion in rat cells.
作为多氯联苯（PCBs）的活性代谢产物，羟基化多氯联苯（OH-PCBs）存在于野生动物和人体组织中。它们被认为是生物体中PCBs内分泌干扰的主要因素。在本研究中，选择单邻位PCB 156及其羟基化代谢产物4'-OH-PCB 159、4'-OH-PCB 121和4'-OH-PCB 72，研究其在1、10²、10⁴ nM浓度下对大鼠肝癌H4IIE细胞系和大鼠甲状腺滤泡FRTL-5细胞系的毒性作用。用微量EROD/PROD法测定7-乙氧基异吩唑酮-O-脱乙基酶（EROD）和7-戊氧基异吩唑酮-O-脱烷基酶（PROD）活性，以指示暴露72小时后H4IIE细胞中细胞色素P4501A1（CYP1A1）和细胞色素P4502B（CYP2B）的诱导情况。为评估这些化合物对甲状腺的干扰作用，在暴露24小时后，用免疫细胞化学法检测FRTL-5细胞内的甲状腺球蛋白浓度，并用放射免疫分析法检测其培养基中的甲状腺球蛋白浓度。观察到10²和10⁴ nM的PCB156能显著诱导EROD活性（p < 0.05），但三种OH-PCBs对H4IIE细胞系无影响。仅10⁴ nM的PCB156和三种OH-PCBs能诱导7-戊氧基异吩唑酮-O-脱烷基酶活性（p < 0.05）。同时，在所有测试浓度下，暴露于4'-OH-PCB 121和4'-OH-PCB 72的FRTL-5细胞培养基中甲状腺球蛋白浓度显著增加（p < 0.05），但其他化合物无此作用。结果表明，单邻位PCBs主要可通过CYP1A1而非CYP2B代谢为羟基化代谢产物。此外，OH-PCBs代谢后仍具有诱导PROD活性的能力，并确实对大鼠细胞中的甲状腺球蛋白合成/分泌有干扰作用。
