ZeTox – Toxicology Services

BY
OUR
PLATFORMS

icon-endocrine-disruption-assay Endocrine Disruption Assay Services

Endocrine-disrupting chemicals (EDCs) are organic and inorganic compounds that affect a variety of hormone-regulated physiological pathways in humans and wildlife. EDCs are produced as plasticizers, pesticides, detergents, and pharmaceuticals compounds, and nowadays are widely spread around the globe. Their actions have been associated with reproductive dysfunction, obesity, cancer and developmental anomalies. Because hormone receptors are highly conserved among vertebrates and particularly responsive in fish, zebrafish embryos are an excellent tool for screening EDCs.

Exposure to EDCs has consequences at different biological levels: from changes in molecular patterns to adverse effects at the organism or population level. Changes at the transcriptomic level (messenger RNA content, mRNA) have been identified as biomarkers of EDC exposure, with a number of potential candidates under evaluation. Cost effective methodologies with low variation, which allow spatial and temporal measurements and can be used in high throughput, are necessary for chemical screening.

Advantages

Evaluation of disrupting effects in a complete organism.

Specific or simultaneous evaluation of impact in the three major endocrine pathways (estrogens, androgens and thyroid) in only one assay.

Applicable to a wide range of compounds, including mixtures. 

Determination of anti-estrogenic and anti-androgenic effects.

Method description

Zebrafish embryos are exposed to the molecule of interest and the three endocrine pathways are assessed individually or simultaneously through transcriptional analysis of a panel of 8 validated gene expression biomarkers. The disruption can be evaluated as activation or repression of the pathway.

Readouts

Determination of the following activities measured as fold induction compared to controls at 120 hpf:

  • Estrogenicity
  • Anti-estrogenicity
  • Androgenicity
  • Anti-androgenicity
  • Thyroid disruption
Figure 1. Example of an estrogenicity study. Dose-response curves for two estrogenic gene expression biomarkers (cy19a1b and vtg1) at 120 hpf after exposure of zebrafish embryos to the natural hormone 17β-estradiol (positive control) and several synthetic chemical compounds with different estrogenic activities.

References

  1. Jarque S, Ibarra J, Rubio-Brotons M, García-Fernández J, Terriente J. Multiplex Analysis Platform for Endocrine Disruption Prediction Using Zebrafish. Int J Mol Sci. 2019 Apr 8;20(7):1739.