Aquatic Ecology and Toxicology Section, Centre for Organismal Studies, University of Heidelberg, Im Neuenheimer Feld 504, D-69120, Heidelberg, Germany.
Aquatic Ecology and Toxicology Section, Centre for Organismal Studies, University of Heidelberg, Im Neuenheimer Feld 504, D-69120, Heidelberg, Germany.
Aquat Toxicol. 2020 Aug;225:105540. doi: 10.1016/j.aquatox.2020.105540. Epub 2020 Jun 12.
The zebrafish (Danio rerio) embryo has increasingly been used as an alternative model in human and environmental toxicology. Since the cytochrome P450 (CYP) system is of fundamental importance for the understanding and correct interpretation of the outcome of toxicological studies, constitutive and xenobiotic-induced 7-methoxycoumarin-O-demethylase (MCOD), i.e. 'mammalian CYP2-like', activities were monitored in vivo in zebrafish embryos via confocal laser scanning microscopy. In order to elucidate molecular mechanisms underlying the MCOD induction, dose-dependent effects of the prototypical CYP inducers β-naphthoflavone (aryl hydrocarbon receptor (AhR) agonist), rifampicin (pregnane X receptor (PXR) agonist), carbamazepine and phenobarbital (constitutive androstane receptor (CAR) agonists) were analyzed in zebrafish embryos of varying age. Starting from 36 h of age, all embryonic stages of zebrafish could be shown to have constitutive MCOD activity, albeit with spatial variation and at distinct levels. Whereas carbamazepine, phenobarbital and rifampicin had no effect on in vivo MCOD activity in 96 h old zebrafish embryos, the model aryl hydrocarbon receptor agonist β-naphthoflavone significantly induced MCOD activity in 96 h old zebrafish embryos at 46-734 nM, however, without a clear concentration-effect relationship. Induction of MCOD activity by β-naphthoflavone gradually decreased with progression of embryonic development. By in vivo characterization of constitutive and xenobiotic-induced MCOD activity patterns in 36, 60, 84 and 108 h old zebrafish embryos, this decrease could primarily be attributed to an age-related decline in the induction of MCOD activity in the cardiovascular system. Results of this study provide novel insights into the mechanism and extent, by which specific CYP activities in early life-stages of zebrafish can be influenced by exposure to xenobiotics. The study thus lends further support to the view that zebrafish embryos- at least from an age of 36 h - have an elaborate and inducible biotransformation system.
斑马鱼（Danio rerio）胚胎越来越多地被用作人类和环境毒理学的替代模型。由于细胞色素 P450（CYP）系统对于理解和正确解释毒理学研究的结果至关重要，因此通过共聚焦激光扫描显微镜在体内监测斑马鱼胚胎中的组成型和外源性诱导的 7-甲氧基香豆素-O-脱甲基酶（MCOD），即“哺乳动物 CYP2 样”活性。为了阐明 MCOD 诱导的分子机制，分析了不同年龄的斑马鱼胚胎中典型 CYP 诱导剂β-萘黄酮（芳烃受体（AhR）激动剂）、利福平（孕烷 X 受体（PXR）激动剂）、卡马西平和苯巴比妥（组成型雄烷受体（CAR）激动剂）的剂量依赖性效应。从 36 小时龄开始，所有斑马鱼胚胎阶段都表现出组成型 MCOD 活性，尽管存在空间变异和不同水平。虽然卡马西平、苯巴比妥和利福平对 96 小时龄的斑马鱼胚胎中的体内 MCOD 活性没有影响，但模型芳烃受体激动剂β-萘黄酮在 46-734 nM 时显著诱导 96 小时龄的斑马鱼胚胎中的 MCOD 活性，但没有明显的浓度-效应关系。MCOD 活性的诱导随着胚胎发育的进展而逐渐降低。通过在 36、60、84 和 108 小时龄的斑马鱼胚胎中体内表征组成型和外源性诱导的 MCOD 活性模式，这种降低主要归因于心血管系统中 MCOD 活性诱导的年龄相关下降。这项研究的结果提供了关于特定 CYP 活性在斑马鱼早期生命阶段如何受到外源性物质暴露影响的机制和程度的新见解。该研究进一步支持了以下观点，即至少从 36 小时龄起，斑马鱼胚胎具有精细的可诱导生物转化系统。
