John Wiley & Sons, Ltd.

A time‐course transcriptional kinetics of the hypothalamic‐pituitary‐gonadal and hypothalamic‐pituitary‐adrenal axes in zebrafish eleuthero‐embryos after exposure to norgestrel

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The objective of this study was to investigate the effects of norgestrel (NGT) on the hypothalamic‐pituitary‐gonadal (HPG) and hypothalamic‐pituitary‐adrenal (HPA) axes in zebrafish eleuthero‐embryos. Zebrafish embryos were exposed to different concentrations of NGT (0, 5, 50 and 100 ng L‐1) for 144 h post fertilization (hpf), and the transcriptional profiles of the HPG and HPA axes were examined every day. NGT modulated the expression of Pgr and Vtg1 mRNAs mainly at 96 hpf for all treatment groups. In addition, NGT strongly altered the expression of Cyp11a1 mRNA above 5 ng L‐1 (significant up‐regulation from 48 to 120 hpf and significant down‐regulation for 144 hpf). NGT treatment could significantly induce expression of Cyp19a1a, Cyp11b, Gnrh2, Gnrh3 and Lhb mRNAs, but inhibit transcripts of Hsd11b2 and Crh genes above 5 ng L‐1 at different time points. The transcriptional expression levels of Esr1, Ar, Star, Hsd17b3, Fshb, and Pomc were also mediated by 5 ng L‐1 NGT or higher during different exposure periods. Taken together, the overall results imply that the transcriptional changes in zebrafish eleuthero‐embryos may pose a potential effect on embryonic development, in particular the brain and gonadogenesis. Environ Toxicol Chem © 2014 SETAC

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