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  • Reversibility of endocrine disruption in zebrafish (Danio rerio) after discontinued exposure to the estrogen 17α-ethinylestradiol.

Reversibility of endocrine disruption in zebrafish (Danio rerio) after discontinued exposure to the estrogen 17α-ethinylestradiol.

Toxicology and applied pharmacology (2014-05-17)
Lisa Baumann, Susanne Knörr, Susanne Keiter, Kristina Rehberger, Sina Volz, Viktoria Schiller, Martina Fenske, Henrik Holbech, Helmut Segner, Thomas Braunbeck
ABSTRACT

The aim of the present study was to investigate the persistence of the feminizing effects of discontinued 17α-ethinylestradiol (EE2) exposure on zebrafish (Danio rerio). An exposure scenario covering the sensitive phase of sexual differentiation, as well as final gonad maturation was chosen to examine the estrogenic effects on sexual development of zebrafish. Two exposure scenarios were compared: continuous exposure to environmentally relevant concentrations (0.1-10 ng/L EE2) up to 100 days post-hatch (dph) and developmental exposure up to 60 dph, followed by 40 days of depuration in clean water. The persistence of effects was investigated at different biological organization levels from mRNA to population-relevant endpoints to cover a broad range of important parameters. EE2 had a strong feminizing and inhibiting effect on the sexual development of zebrafish. Brain aromatase (cyp19b) mRNA expression showed no clear response, but vitellogenin levels were significantly elevated, gonad maturation and body growth were inhibited in both genders, and sex ratios were skewed towards females and undifferentiated individuals. To a large extent, all of these effects were reversed after 40 days of recovery, leading to the conclusion that exposure to the estrogen EE2 results in very strong, but reversible underdevelopment and feminization of zebrafish. The present study is the first to show this reversibility at different levels of organization, which gives better insight into the mechanistic basis of estrogenic effects in zebrafish.

MATERIALS
Product Number
Brand
Product Description

Ethinylestradiol for system suitability, European Pharmacopoeia (EP) Reference Standard
Sigma-Aldrich
17α-Ethynylestradiol, ≥98%
Ethinylestradiol, European Pharmacopoeia (EP) Reference Standard
Supelco
17α-Ethynylestradiol solution, 1.0 mg/mL in methanol, ampule of 1 mL, certified reference material, Cerilliant®
Supelco
Ethinyl Estradiol, Pharmaceutical Secondary Standard; Certified Reference Material
USP
Ethinyl estradiol, United States Pharmacopeia (USP) Reference Standard