title: Sexual disruption in zebrafish (Danio rerio) exposed to mixtures of 17α-ethinylestradiol and 17β-trenbolone.
abstract: Environmental estrogens and androgens can be present simultaneously in aquatic environments and thereby interact to disturb multiple physiological systems in organisms. Studies on interaction effects in fish of androgenic and estrogenic chemicals are limited. Therefore, the aim of the present study was to evaluate feminization and masculinization effects in zebrafish (Danio rerio) exposed to combinations of two synthetic steroid hormones detected in environmental waters: the androgen 17β-trenbolone (Tb) and the oestrogen 17α-ethinylestradiol (EE2). Juvenile zebrafish were exposed between days 20 and 60 post-hatch to different binary mixtures of Tb (1, 10, and 50 ng/L) and EE2 (2 and 5 ng/L). The endpoints studied were whole-body homogenate vitellogenin concentration at 40 days post-hatch, and sex ratio including gonad maturation at 60 days post-hatch. The feminizing potency of 5 ng/L of EE2, alone as well as in combination with Tb, was clear in the present study, with exposures resulting in almost all-female populations and females being sexually immature. Masculinization effects with male-biased sex ratios were observed when fish were exposed to 2 ng/L of EE2 in combination with Tb concentrations. Intersex fish were observed after exposure to mixtures of 2 ng/L EE2 with 50 ng/L Tb. Sexual maturity generally increased among males at increasing concentrations of Tb. The results of the present study show that exposure to environmentally relevant mixtures of an oestrogen and androgen affects the process of gonad differentiation in zebrafish and lead to sexual disruption.
authors.affiliation: Department of Biomedical Sciences & Veterinary Public Health, Swedish University of Agricultural Sciences, P.O. Box 7028, SE-75007 Uppsala, Sweden. Electronic address: Stefan.Orn@slu.se.
authors.forename: Stefan
authors.initials: S
authors.lastname: Örn
authors.affiliation: Department of Biology, University of Southern Denmark, Campusvej 55, DK-5230 Odense, Denmark.
authors.forename: Henrik
authors.initials: H
authors.lastname: Holbech
authors.affiliation: Department of Biomedical Sciences & Veterinary Public Health, Swedish University of Agricultural Sciences, P.O. Box 7028, SE-75007 Uppsala, Sweden.
authors.forename: Leif
authors.initials: L
authors.lastname: Norrgren
mesh_terms: D000818:Animals; D004997:Ethinyl Estradiol / Q000633:toxicity*; D005260:Female; D006066:Gonads / Q000187:drug effects / Q000254:growth & development; D008297:Male; D012727:Sex Characteristics; D012733:Sex Differentiation / Q000187:drug effects*; D012741:Sexual Maturation / Q000187:drug effects*; D014204:Trenbolone Acetate / Q000633:toxicity*; D014819:Vitellogenins / Q000032:analysis; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000633:toxicity; D015027:Zebrafish / Q000502:physiology*
chemical_list: D014819:Vitellogenins; D014874:Water Pollutants, Chemical; D004997:Ethinyl Estradiol; D014204:Trenbolone Acetate
keywords: 17α-Ethinylestradiol; 17β-Trenbolone; Danio rerio; Sex ratio; Vitellogenin; Zebrafish