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Effects on differentiation of reproductive organs and sexual behaviour in Japanese quail by excessive embryonic ERα activation
Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Physiology and Developmental Biology, Environmental Toxicology.
Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Physiology and Developmental Biology, Environmental Toxicology.
2010 (English)In: Reproduction, Fertility and Development, ISSN 1031-3613, Vol. 22, no 2, 416-425 p.Article in journal (Refereed) Published
Abstract [en]

Exposure of Japanese quail (Coturnix japonica) embryos to oestrogenic substances disrupts sexual differentiation of the reproductive tract of both sexes and impairs the copulatory behaviour of the adult male. To examine whether these effects can be induced by selective activation of oestrogen receptor alpha (ER alpha), Japanese quail eggs were injected with various doses of the selective ER alpha agonist 16 alpha-lactone-oestradiol (16 alpha-LE2). The natural oestrogen 17 beta-oestradiol (E-2) was used as a positive control. Both 16 alpha-LE2 and E-2 induced formation of an ovary-like cortex in the left testis (ovotestis) and reduced the size of the right testis in male embryos. The asymmetry in testis size remained in sexually mature males. Both substances induced retention and malformation of the Mullerian ducts in embryos of both sexes and malformed oviducts in juveniles. Male copulatory behaviour was suppressed by embryonic exposure to E-2 and the highest dose of 16 alpha-LE2. However, the lower dose of 16 alpha-LE2, which markedly affected development of the reproductive organs, was without effects on behaviour. It can therefore not be excluded that the behavioural demasculinisation at the 100-fold higher dose involved cross-activation of oestrogen receptor beta (ER beta). In conclusion, our results suggest that oestrogen-induced disruption of reproductive organ development in Japanese quail can be mediated via ER alpha, whereas the role of ER alpha in demasculinisation of copulatory behaviour remains to be clarified.

Place, publisher, year, edition, pages
2010. Vol. 22, no 2, 416-425 p.
Keyword [en]
endocrine disruption; oestrogen receptors; ovotestis; sex differentiation
National Category
Biological Sciences
URN: urn:nbn:se:uu:diva-97341DOI: 10.1071/RD08293ISI: 000273208800003OAI: oai:DiVA.org:uu-97341DiVA: diva2:172233
Available from: 2008-05-22 Created: 2008-05-22 Last updated: 2011-01-11Bibliographically approved
In thesis
1. Roles of ERα and ERβ in Normal and Disrupted Sex Differentiation in Japanese Quail
Open this publication in new window or tab >>Roles of ERα and ERβ in Normal and Disrupted Sex Differentiation in Japanese Quail
2008 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Exposure to xenoestrogens during development has been shown to impair sexual differentiation in various species. The major aim of this thesis was to elucidate the respective roles of the two estrogen receptors ERα and ERβ in normal and disrupted differentiation of sex organs and copulatory behavior in the Japanese quail (Coturnix japonica). The expression of ERα mRNA was much stronger than that of ERβ mRNA in the gonads and Müllerian ducts (embryonic oviducts) in early embryos. By contrast, ERβ seemed to be predominantly expressed in regions of the embryonic brain that are associated with male sexual behavior. Embryos were exposed to the selective ERα agonists propyl-pyrazole-triol (PPT) and 16α-lactone-estradiol (16α-LE2). The estrogens 17β-estradiol (E2) and 17α-ethynylestradiol (EE2), which activate both ERα and ERβ, were used as positive controls. All substances impaired reproductive organ differentiation. The effects observed included oviductal malformations in females and partial development of oviducts in males. All substances also induced testis feminization (ovotestis) in male embryos. The male copulatory behavior was severely impaired by the positive controls but was unaffected by PPT and 16α-LE2 at doses that disrupted sex organ differentiation. A higher dose of 16α-LE2 significantly suppressed the behavior. However, it is possible that this effect was caused by cross-activation of ERβ. The substances also induced hepatic expression of mRNA encoding the egg-yolk proteins vitellogenin II and very low-density apolipoprotein II, which are commonly used as indicators of estrogen exposure. In conclusion, the results suggest that ERα is important for female reproductive organ differentiation. Excess activation of ERα by xenoestrogens impairs differentiation in both females and males and induces hepatic expression of egg-yolk proteins. The results also indicate that ERα alone cannot mediate demasculinization of male copulatory behavior in quail, although further studies are needed to test this hypothesis.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2008. 68 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 445
Toxicology, sex differentiation, estrogen receptor, sexual behavior, endocrine disruption, Japanese quail, Toxikologi
urn:nbn:se:uu:diva-8921 (URN)978-91-554-7232-0 (ISBN)
Public defence
2008-06-12, Lindahlsalen, Evolutionsbiologiskt centrum (EBC), Norbyvägen 18A, Uppsala, 13:15 (English)
Available from: 2008-05-22 Created: 2008-05-22 Last updated: 2010-01-07Bibliographically approved

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