Fluorotelomer alcohols induce hepatic vitellogenin through activation of the estrogen receptor in male medaka (Oryzias latipes)

Here we report on the in vivo estrogenic effects of two fluorotelomer alcohols, such as 1H,1H,2H,2H-perfluorooctan-1-ol (6:2 FTOH) and 1H,1H,2H,2H-perfluorodecan-1-ol (8:2 FTOH), in male medaka (Oryzias latipes). An in vitro yeast two-hybrid assay indicated a significant, dose-dependent interaction between medaka estrogen receptor α (ERα) and coactivator TIF2 upon treatment with 6:2 FTOH, 8:2 FTOH or 2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10-nonadecafluoro-1-decanol (NFDH). The relative ranks of tested chemicals on the estrogenic effects for medaka ERα descended in the order of estradiol-17β (100) ≫ 6:2 FTOH (0.16) > NFDH (0.016) > 8:2 FTOH (0.0044). In contrast, no interaction with the ERα was observed upon treatment with perfluorooctane sulfonate (PFOS), perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), perfluorododecanoic acid (PFDA) or perfluoroundecanoic acid (PFUnDA). Expression analysis of hepatic vitellogenin (VTG) protein showed estrogenic potentials with, 6:2 FTOH and 8:2 FTOH, indicative of the induction of VTG synthesis in the livers of male medaka. We also investigated mRNA expression levels of two ER subtypes (ERα and β) and two VTGs (VTG I and VTG II) in the livers of male medaka following exposure to FTOHs. Quantitative real-time polymerase chain reaction analyses revealed that hepatic ERα, VTG I, and VTG II mRNA responded rapidly to FTOHs such as 6:2 FTOH and 8:2 FTOH after 8-h exposure, whereas no effects of these compounds on ERβ mRNA transcription were observed. These results from both in vitro and in vivo assays strongly suggest that certain FTOHs, such as 6:2 FTOH and 8:2 FTOH, induce hepatic VTG through activation of ERα in male medaka.