Rehberger Kristina, Baumann Lisa, Hecker Markus, Braunbeck Thomas
Centre for Organismal Studies, Aquatic Ecology and Toxicology, University of Heidelberg, Im Neuenheimer Feld 504, 69120, Heidelberg, Germany.
Vetsuisse Faculty, Centre for Fish and Wildlife Health, University of Bern, Länggassstrasse122, 3012, Bern, Switzerland.
Fish Physiol Biochem. 2018 Jun;44(3):997-1010. doi: 10.1007/s10695-018-0488-y. Epub 2018 Mar 22.
Endocrine-disrupting chemicals are known to impact multiple hormonal axes of vertebrates, among which the thyroid system is crucial for multiple developmental and physiological processes. Thus, the present study focused on the semi-quantitative visualization of intrafollicular triiodothyronine (T3) and thyroxin (T4) in zebrafish embryos as a potential test system for the detection of disrupted thyroid hormone synthesis. To this end, an antibody-based fluorescence double-staining protocol for whole-mount zebrafish embryos and larvae was adapted to simultaneously detect intrafollicular T3 and T4. During normal development until 10 days post-fertilization (dpf), the number of thyroid follicles increased along the ventral aorta. Concentrations of T4 and T3, measured by fluorescence intensity, increased until 6 dpf, but decreased thereafter. Exposure of zebrafish embryos to propylthiouracil (PTU), a known inhibitor of TH synthesis, resulted in a significant decrease in the number of follicles that stained for T3, whereas a trend for increase in follicles that stained for T4 was observed. In contrast, fluorescence intensity for both thyroid hormones decreased significantly after exposure to PTU. Overall, the zebrafish embryo appears to be suitable for the simultaneous visualization and detection of changing intrafollicular TH contents during normal development and after PTU treatment.
已知内分泌干扰化学物质会影响脊椎动物的多个激素轴，其中甲状腺系统对多种发育和生理过程至关重要。因此，本研究聚焦于斑马鱼胚胎中滤泡内三碘甲状腺原氨酸（T3）和甲状腺素（T4）的半定量可视化，将其作为检测甲状腺激素合成紊乱的潜在测试系统。为此，一种基于抗体的针对斑马鱼胚胎和幼体整体标本的荧光双重染色方案被加以调整，以同时检测滤泡内的T3和T4。在正常发育至受精后10天（dpf）期间，甲状腺滤泡的数量沿着腹主动脉增加。通过荧光强度测量的T4和T3浓度在6 dpf之前增加，但之后下降。将斑马鱼胚胎暴露于已知的甲状腺激素合成抑制剂丙硫氧嘧啶（PTU），导致T3染色的滤泡数量显著减少，而观察到T4染色的滤泡有增加趋势。相比之下，暴露于PTU后，两种甲状腺激素的荧光强度均显著降低。总体而言，斑马鱼胚胎似乎适合在正常发育期间以及PTU处理后同时可视化和检测滤泡内甲状腺激素含量的变化。
