title: Environmentally relevant concentrations of 17alpha-ethinylestradiol (EE2) interfere with the growth hormone (GH)/insulin-like growth factor (IGF)-I system in developing bony fish.
abstract: The aim of this study was to evaluate whether effects of environmental estrogens on fish growth and reproduction may be mediated via modulating the growth hormone (GH)/insulin-like growth factor I (IGF-I) system. To this end, developing male and female monosex populations of tilapia were exposed to 17alpha-ethinylestradiol (EE2) at 5 and 25 ng EE2/l water from 10-day postfertilization (DPF) until 100 DPF. Under exposure to both EE2 concentrations, sex ratio shifted toward more females and body length, and weight were significantly reduced in males. The growth-reducing effect was associated with significant changes in hepatic IGF-I expression, both in males and females and with significant alterations of IGF-I mRNA and GH mRNA in the brain. The changes in IGF-I and GH mRNA were accompanied by altered estrogen receptor alpha (ERalpha) expression in brain and liver. These findings point to an influence of estrogenic exposure on the endocrine GH/IGF-I axis. In addition, the EE2 treatment resulted in significant changes of ERalpha and IGF-I expression in ovaries and testis, suggesting that the estrogens interact not only with the endocrine but also with the autocrine/paracrine part of the IGF-I system. Overall, our results provide evidence that EE2 at environmentally relevant concentrations is able to interfere with the GH/IGF-I system in bony fish and that the impairing effects of estrogens reported on fish growth and reproductive functions may rather result from a cross talk between the sex steroid and the IGF-I system than be toxicological.
authors.affiliation: Division of Neuroendocrinology, Institute of Anatomy, University of Zürich, Zürich, Switzerland.
authors.forename: Natallia
authors.initials: N
authors.lastname: Shved
authors.forename: Giorgi
authors.initials: G
authors.lastname: Berishvili
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Baroiller
authors.forename: Helmut
authors.initials: H
authors.lastname: Segner
authors.forename: Manfred
authors.initials: M
authors.lastname: Reinecke
mesh_terms: D000818:Animals; D049628:Body Size / Q000187:drug effects; D001921:Brain / Q000187:drug effects / Q000196:embryology / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D052244:Endocrine Disruptors / Q000633:toxicity*; D047628:Estrogen Receptor alpha / Q000378:metabolism; D004997:Ethinyl Estradiol / Q000633:toxicity*; D005260:Female; D029941:Fish Proteins / Q000235:genetics / Q000378:metabolism*; D013006:Growth Hormone / Q000235:genetics / Q000378:metabolism*; D007334:Insulin-Like Growth Factor I / Q000235:genetics / Q000378:metabolism*; D008099:Liver / Q000187:drug effects / Q000196:embryology / Q000378:metabolism; D008297:Male; D010053:Ovary / Q000187:drug effects / Q000196:embryology / Q000378:metabolism; D010902:Pituitary Gland / Q000187:drug effects / Q000196:embryology / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D012744:Sex Ratio; D013737:Testis / Q000187:drug effects / Q000196:embryology / Q000378:metabolism; D017210:Tilapia / Q000196:embryology / Q000378:metabolism*; D014874:Water Pollutants, Chemical / Q000633:toxicity*
chemical_list: D052244:Endocrine Disruptors; D047628:Estrogen Receptor alpha; D029941:Fish Proteins; D012333:RNA, Messenger; D014874:Water Pollutants, Chemical; D004997:Ethinyl Estradiol; D007334:Insulin-Like Growth Factor I; D013006:Growth Hormone