title: Zebrafish sex differentiation and gonad development after exposure to 17α-ethinylestradiol, fadrozole and their binary mixture: A stereological study.
abstract: Current knowledge on zebrafish (Danio rerio) sex determination suggests that this trait has a polygenic genetic basis, although environmental factors, such as endocrine disrupting chemicals (EDC), may also be involved in modeling or disturbing the species sex differentiation and development. This study aimed to assess how sex steroids imbalance triggers impact on sex differentiation and gonad development in zebrafish. Fish where exposed to an estrogen (EE2, i.e. 17α-ethinylestradiol, 4ng/L), to an inhibitor of estrogen synthesis (Fad, i.e. fadrozole, 50μg/L) or to their binary mixture (Mix-EE2+ Fad, 4ng/L+50μg/L), from 2h to 60 days post-fertilization (dpf). Afterwards, a quantitative (stereological) analysis using light microscopy, based on systematic sampling, was made at 35 and 60dpf, to identify alterations on gonad differentiation and development. During the sex differentiation period, our histological data showed that not all zebrafish males develop a "juvenile ovary", contrarily to what is currently taken for granted. Furthermore, the stereological analysis suggests that EE2 alone enhanced both zebrafish growth and gonad development. On the other hand, exposure to Fad affected the sexual development in zebrafish, inducing masculinization of the specimens, with some degree of intersex observed in males. In addition, the binary mixture allowed identifying sex-dependent roles of steroid hormones in the general growth and gonad development of zebrafish, with estrogens acting as growth promoters in females and being essential for ovary development. Data further support that sex-specific and single EDC impact studies are important, but clearly not sufficient to understand what may occur in the environment.
authors.affiliation: Centre for the Research and Technology of Agro-Environmental and Biological Sciences, CITAB, Departamento de Biologia e Ambiente (DeBA), Escola de Ciências da Vida e Ambiente (ECVA), University of Trás-os-Montes and Alto Douro, UTAD, Quinta de Prados, 5000-801, Vila Real, Portugal(1). Electronic address: aluzio@utad.pt.
authors.forename: Ana
authors.initials: A
authors.lastname: Luzio
authors.affiliation: Centre for the Research and Technology of Agro-Environmental and Biological Sciences, CITAB, Departamento de Biologia e Ambiente (DeBA), Escola de Ciências da Vida e Ambiente (ECVA), University of Trás-os-Montes and Alto Douro, UTAD, Quinta de Prados, 5000-801, Vila Real, Portugal(1).
authors.forename: Sandra M
authors.initials: SM
authors.lastname: Monteiro
authors.affiliation: Centre for the Research and Technology of Agro-Environmental and Biological Sciences, CITAB, Departamento de Biologia e Ambiente (DeBA), Escola de Ciências da Vida e Ambiente (ECVA), University of Trás-os-Montes and Alto Douro, UTAD, Quinta de Prados, 5000-801, Vila Real, Portugal(1).
authors.forename: Sofia
authors.initials: S
authors.lastname: Garcia-Santos
authors.affiliation: Laboratory of Histology and Embryology, Department of Microscopy, Institute of Biomedical Sciences Abel Salazar (ICBAS), University of Porto (U. Porto), Portugal; Histomorphology, Physiopathology and Applied Toxicology Group, Interdisciplinary Centre of Marine and Environmental Research (CIIMAR), CIMAR Associated Laboratory (CIMAR LA), University of Porto (U. Porto), Portugal.
authors.forename: Eduardo
authors.initials: E
authors.lastname: Rocha
authors.affiliation: Centre for the Research and Technology of Agro-Environmental and Biological Sciences, CITAB, Departamento de Biologia e Ambiente (DeBA), Escola de Ciências da Vida e Ambiente (ECVA), University of Trás-os-Montes and Alto Douro, UTAD, Quinta de Prados, 5000-801, Vila Real, Portugal(1).
authors.forename: António A
authors.initials: AA
authors.lastname: Fontaínhas-Fernandes
authors.affiliation: Centre for the Research and Technology of Agro-Environmental and Biological Sciences, CITAB, Departamento de Biologia e Ambiente (DeBA), Escola de Ciências da Vida e Ambiente (ECVA), University of Trás-os-Montes and Alto Douro, UTAD, Quinta de Prados, 5000-801, Vila Real, Portugal(1). Electronic address: acoimbra@utad.pt.
authors.forename: Ana M
authors.initials: AM
authors.lastname: Coimbra
mesh_terms: D000818:Animals; D004357:Drug Synergism; D052244:Endocrine Disruptors / Q000633:toxicity; D004997:Ethinyl Estradiol / Q000633:toxicity*; D017316:Fadrozole / Q000633:toxicity*; D005260:Female; D006066:Gonads / Q000187:drug effects*; D008297:Male; D012733:Sex Differentiation / Q000187:drug effects*; D046468:Sexual Development / Q000187:drug effects; D014874:Water Pollutants, Chemical / Q000633:toxicity*; D015027:Zebrafish / Q000235:genetics
chemical_list: D052244:Endocrine Disruptors; D014874:Water Pollutants, Chemical; D004997:Ethinyl Estradiol; D017316:Fadrozole
keywords: 17α-Ethinylestradiol; Fadrozole; Gonad; Histology; Sex differentiation