Zebrafishlab, Veterinary Physiology and Biochemistry, Department of Veterinary Sciences, University of Antwerp, Wilrijk, Belgium.
Systemic Physiological and Ecotoxicological Research, Department of Biology, University of Antwerp, Antwerp, Belgium.
Environ Toxicol Chem. 2019 Mar;38(3):533-547. doi: 10.1002/etc.4343. Epub 2019 Feb 11.
Fish (embryo) toxicity test guidelines are mostly based on aquatic exposures. However, in some cases, other exposure routes can be more practical and relevant. Micro-injection into the yolk of fish embryos could offer a particular advantage for administering hydrophobic compounds, such as many endocrine disruptors. Single-dose micro-injection was compared with continuous aquatic exposure in terms of compound accumulation and biological responses. 17α-Ethinyl estradiol (EE2) was used as a model compound. First, the optimal solvent and droplet size were optimized, and needle variation was assessed. Next, biological endpoints were evaluated. The accumulated internal dose of EE2 decreased over time in both exposure scenarios. Estrogen receptor activation was concentration/injected dose dependent, increased daily, and was related to esr2b transcription. Transcription of vitellogenin 1 (vtg1) and brain aromatase (cyp19a1b) was induced in both scenarios, but the cyp19a1b transcription pattern differed between routes. Injection caused an increase in cyp19a1b transcripts from 48 hours post fertilization (hpf) onward, whereas after aquatic exposure the main increase occurred between 96 and 120 hpf. Some malformations only occurred after injection, whereas others were present for both scenarios. We conclude that responses can differ between exposure routes and therefore micro-injection is not a direct substitute for, but can be complementary to aquatic exposure. Nevertheless, vtg1and cyp19a1b transcription and estrogen receptor activation are suitable biomarkers for endocrine disruptor screening in both scenarios. Environ Toxicol Chem 2019;38:533-547. © 2018 SETAC.
鱼类（胚胎）毒性测试指南主要基于水生暴露。然而，在某些情况下，其他暴露途径可能更实际和相关。将化合物微注射到鱼胚胎的卵黄中，对于投与疏水性化合物（如许多内分泌干扰物）可能具有特殊优势。在化合物积累和生物反应方面，单次剂量微注射与连续水生暴露进行了比较。17α-乙炔基雌二醇（EE2）被用作模型化合物。首先，优化了最佳溶剂和液滴大小，并评估了针头变化。接下来，评估了生物学终点。在两种暴露情况下，EE2 的累积内部剂量随时间而降低。雌激素受体激活与浓度/注射剂量有关，且呈每日增加趋势，并与 esr2b 转录有关。两种情况下均诱导了卵黄蛋白原 1（vtg1）和脑芳香酶（cyp19a1b）的转录，但转录模式因途径而异。注射会导致 cyp19a1b 转录物从受精后 48 小时（hpf）开始增加，而在水生暴露后，主要增加发生在 96 和 120 hpf 之间。一些畸形仅在注射后发生，而另一些畸形则在两种情况下均存在。我们得出的结论是，由于暴露途径不同，反应可能会有所不同，因此微注射不是水生暴露的直接替代品，但可以与之互补。尽管如此，vtg1 和 cyp19a1b 转录和雌激素受体激活仍然是两种情况下筛选内分泌干扰物的合适生物标志物。Environ Toxicol Chem 2019;38:533-547. © 2018 SETAC.
