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Short-term treatment of adult male zebrafish (Danio Rerio) with 17α-ethinyl estradiol affects the transcription of genes involved in development and male sex differentiation.
Södertörn University, School of Natural Sciences, Technology and Environmental Studies, Biology. Örebro University.
Södertörn University, School of Natural Sciences, Technology and Environmental Studies, Biology. Örebro University.
Södertörn University, School of Natural Sciences, Technology and Environmental Studies, Biology.
Örebro University.
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2014 (English)In: Comparative Biochemistry and Physiology - Part C: Toxicology & Pharmacology, ISSN 1532-0456, E-ISSN 1878-1659, Vol. 164, 35-42 p.Article in journal (Refereed) Published
Abstract [en]

The synthetic estrogen 17α-ethinyl estradiol (EE2) disturbs reproduction and causes gonadal malformation in fish. Effects on the transcription of genes involved in gonad development and function that could serve as sensitive biomarkers of reproductive effects in the field is, however, not well known. We have studied mRNA expression in testes and liver of adult zebrafish (Danio rerio) males treated with 0, 5 or 25ng/L EE2for 14days. qPCR analysis showed that the mRNA expression of four genes linked to zebrafish male sex determination and differentiation, Anti-Mullerian Hormone, Double sex and mab-related protein, Sry-related HMG box-9a and Nuclear receptor subfamily 5 group number 1b were significantly decreased by 25ng/L, but not 5ng/L EE2 compared with the levels in untreated fish. The decreased transcription was correlated with a previously shown spawning failure in these males (Reyhanian et al., 2011. Aquat Toxicol 105, 41-48), suggesting that decreased mRNA expression of genes regulating male sexual function could be involved in the functional sterility. The mRNA level of Cytochrome P-45019a, involved in female reproductive development, was unaffected by hormone treatment. The transcription of the female-specific Vitellogenin was significantly induced in testes. While testicular Androgen Receptor and the Estrogen Receptor-alpha mRNA levels were unchanged, Estrogen receptor-beta was significantly decreased by 25ng/L EE2. Hepatic Estrogen Receptor-alpha mRNA was significantly increased by both exposure concentrations, while Estrogen Receptor-beta transcription was unaltered. The decreased transcription of male-predominant genes supports a demasculinization of testes by EE2 and might reflect reproductive disturbances in the environment.

Place, publisher, year, edition, pages
2014. Vol. 164, 35-42 p.
Keyword [en]
landscape scars, industrial heritage, waste, nuclear power, mining, Malmberget, Ignalina, Sweden, Lithuania
National Category
Biological Sciences
Identifiers
URN: urn:nbn:se:sh:diva-23362DOI: 10.1016/j.cbpc.2014.04.003ISI: 000337769100005PubMedID: 24747828ScopusID: 2-s2.0-84899872779OAI: oai:DiVA.org:sh-23362DiVA: diva2:714261
Funder
The Foundation for Baltic and East European Studies
Available from: 2014-04-25 Created: 2014-04-25 Last updated: 2016-10-04Bibliographically approved
In thesis
1. Hitting the mark: Studies of alterations in behaviour and fertility in ethinyl estradiol-exposed zebrafish and search related biomarkers
Open this publication in new window or tab >>Hitting the mark: Studies of alterations in behaviour and fertility in ethinyl estradiol-exposed zebrafish and search related biomarkers
2016 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

In this thesis, we have analysed the effects of EE2 on non-reproductive behaviours and fertility. We have showed that two doses of EE2 in male adult short-term exposures evokes opposite behaviours in the novel tank test. A lower dose induced increased bottom-dwelling, a sign of increased anxiety and a higher dose increased surface-dwelling, which would likely expose themselves to predation in a natural environment. Increased shoaling was observed in both exposures, possibly affecting feeding and reproduction opportunities. Fertility analysis of these fish demonstrated a complete inhibition of spawning in the highest dose group. To investigate mechanisms behind the spawning failure, we examined expression levels of genes involved in zebrafish sex differentiation and maintenance of gonadal function. We found downregulated transcription levels of male-predominant genes, suggesting a demasculinization of the testes contributing to functional sterility in these fish. We have demonstrated that non-reproductive behaviour in zebrafish is highly sensitive to EE2 exposure during development. After exposing male and female zebrafish to low doses of EE2 followed by remediation in clean water until adulthood, the fish displayed increased anxiety and shoaling behaviour, demonstrating persistent effects of EE2. Furthermore, behavioural effects were transferred to their progeny. Decreased fertilisation success of the developmentally exposed fish was observed in both sexes when mated to untreated animals of the opposite sex. These fertility effects persisted although the fish had a long remediation period, implying likely reduced fitness of fish populations in aquatic environments. Based on our findings on non-reproductive behaviours and fertility, we performed RNAsequencing analysis of the brain and testes in order to investigate possible biological mechanisms behind the persistent effects. There is a need for biomarkers allowing detection of both reversible and irreversible effects in animals exposed to estrogenic substances, hopefully contributing to better risk assessments for EDCs. Results from RNA-sequencing would serve as a basis for continued studies in pursuit of potential biomarkers.

Place, publisher, year, edition, pages
Örebro: Örebro university, 2016. 55 p.
Series
Örebro Studies in Biology, ISSN 1650-8793 ; 10Södertörn doctoral dissertations, ISSN 1652-7399 ; 115
Keyword
Endocrine disrupting compounds, 17α-ethinylestradiol, fertility, anxiety, behaviour, zebrafish, biomarkers, stress
National Category
Other Biological Topics
Identifiers
urn:nbn:se:sh:diva-29440 (URN)978-91-7529-115-4 (ISBN)
Public defence
2016-02-25, Sal MA636, Alfred Nobels allé 7, Huddinge, 13:00 (English)
Opponent
Supervisors
Funder
The Foundation for Baltic and East European Studies
Available from: 2016-02-04 Created: 2016-02-04 Last updated: 2016-02-04Bibliographically approved

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