title: In ovo treatment with an estrogen receptor alpha selective agonist causes precocious development of the female reproductive tract of the American alligator (Alligator mississippiensis).
abstract: The molecular signaling processes involved the differentiation of the Müllerian duct (MD) into the female reproductive tract, or oviduct, in non-mammalian vertebrates are not well understood. Studies in mammals and birds indicate that steroid hormones play a role in this process, as the embryonic MD has been shown to be vulnerable to exogenous estrogens and progestins and environmental endocrine disrupting contaminants. In a previous study, developmental treatment with an estrogen receptor α (ERα) agonist, 4,4',4″-(4-propyl-[1H]-pyrazole-1,3,5-triyl)trisphenol (PPT), induced significant enlargement of the MD in alligator embryos incubated at a male-producing temperature, which was not observed in embryos treated with an estrogen receptor β (ERβ) agonist, 7-bromo-2-(4-hydroxyphenyl)-1,3-benzoxazol-5-ol (WAY 200070), or with 17β-estradiol (E2). In order to understand the role of estrogen signaling in female alligator oviduct development, we incubated eggs at a female-producing temperature and treated them with E2and these ER selective agonists, PPT and WAY 200070, just prior to the thermosensitive window of sex determination. At stage 27, one stage prior to hatching, PPT induced significant enlargement of the MD with precocious development of secretory glands and connective tissue differentiation similar to characteristics of mature adult oviduct. PPT treatment in ovo increased mRNA expression of ERβ, progesterone receptor, androgen receptor and insulin-like growth factor 1 in MD at stage 27, while expression of ERα was decreased. Neither WAY 200070 nor E2treatment induced these effects seen in PPT-treated MD. The results of this study provide insight into the critical factors for healthy reproductive system formation in this sentinel species, although further investigation is needed to determine whether the observed phenomena are directly due to selective stimulation of ERα or related to some other aspect of PPT treatment.
authors.affiliation: Department of Obstetrics and Gynecology, Medical University of South Carolina, Hollings Marine Laboratory, Charleston, SC 29412, USA. Electronic address: bdoheny@gmail.com.
authors.forename: Brenna M
authors.initials: BM
authors.lastname: Doheny
authors.affiliation: Department of Obstetrics and Gynecology, Medical University of South Carolina, Hollings Marine Laboratory, Charleston, SC 29412, USA.
authors.forename: Satomi
authors.initials: S
authors.lastname: Kohno
authors.affiliation: Department of Obstetrics and Gynecology, Medical University of South Carolina, Hollings Marine Laboratory, Charleston, SC 29412, USA.
authors.forename: Benjamin B
authors.initials: BB
authors.lastname: Parrott
authors.affiliation: Department of Obstetrics and Gynecology, Medical University of South Carolina, Hollings Marine Laboratory, Charleston, SC 29412, USA.
authors.forename: Louis J
authors.initials: LJ
authors.lastname: Guillette
mesh_terms: D000489:Alligators and Crocodiles / Q000196:embryology* / Q000378:metabolism*; D000818:Animals; D004625:Embryo, Nonmammalian / Q000187:drug effects; D004847:Epithelial Cells / Q000166:cytology / Q000187:drug effects; D047628:Estrogen Receptor alpha / Q000819:agonists* / Q000378:metabolism; D005260:Female; D005836:Genitalia, Female / Q000187:drug effects / Q000196:embryology*; D007334:Insulin-Like Growth Factor I / Q000235:genetics / Q000378:metabolism; D009095:Mullerian Ducts / Q000187:drug effects / Q000196:embryology / Q000378:metabolism; D010080:Oxazoles / Q000494:pharmacology; D010636:Phenols / Q000494:pharmacology; D011720:Pyrazoles / Q000494:pharmacology; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D014481:United States
chemical_list: D047628:Estrogen Receptor alpha; D010080:Oxazoles; D010636:Phenols; D011720:Pyrazoles; D012333:RNA, Messenger; C502077:WAY 200070; C486184:4,4',4''-(4-propyl-((1)H)-pyrazole-1,3,5-triyl) tris-phenol; D007334:Insulin-Like Growth Factor I
keywords: Alligator; Estrogen receptor; IGF-1; Oviduct