title: Wastewater treatment plant effluent alters pituitary gland gonadotropin mRNA levels in juvenile coho salmon (Oncorhynchus kisutch).
abstract: It is well known that endocrine disrupting compounds (EDCs) present in wastewater treatment plant (WWTP) effluents interfere with reproduction in fish, including altered gonad development and induction of vitellogenin (Vtg), a female-specific egg yolk protein precursor produced in the liver. As a result, studies have focused on the effects of EDC exposure on the gonad and liver. However, impacts of environmental EDC exposure at higher levels of the hypothalamic-pituitary-gonad axis are less well understood. The pituitary gonadotropins, follicle-stimulating hormone (Fsh) and luteinizing hormone (Lh) are involved in all aspects of gonad development and are subject to feedback from gonadal steroids making them a likely target of endocrine disruption. In this study, the effects of WWTP effluent exposure on pituitary gonadotropin mRNA expression were investigated to assess the utility of Lh beta-subunit (lhb) as a biomarker of estrogen exposure in juvenile coho salmon (Oncorhynchus kisutch). First, a controlled 72-h exposure to 17α-ethynylestradiol (EE2) and 17β-trenbolone (TREN) was performed to evaluate the response of juvenile coho salmon to EDC exposure. Second, juvenile coho salmon were exposed to 0, 20 or 100% effluent from eight WWTPs from the Puget Sound, WA region for 72h. Juvenile coho salmon exposed to 2 and 10ng EE2L(-1) had 17-fold and 215-fold higher lhb mRNA levels relative to control fish. Hepatic vtg mRNA levels were dramatically increased 6670-fold, but only in response to 10ng EE2L(-1) and Fsh beta-subunit (fshb) mRNA levels were not altered by any of the treatments. In the WWTP effluent exposures, lhb mRNA levels were significantly elevated in fish exposed to five of the WWTP effluents. In contrast, transcript levels of vtg were not affected by any of the WWTP effluent exposures. Mean levels of natural and synthetic estrogens in fish bile were consistent with pituitary lhb expression, suggesting that the observed lhb induction may be due to estrogenic activity of the WWTP effluents. These results suggest that lhb gene expression may be a sensitive index of acute exposure to estrogenic chemicals in juvenile coho salmon. Further work is needed to determine the kinetics and specificity of lhb induction to evaluate its utility as a potential indicator of estrogen exposure in immature fish.
authors.affiliation: School of Aquatic and Fishery Sciences, University of Washington, Seattle, WA 98195, USA.
authors.forename: Louisa B
authors.initials: LB
authors.lastname: Harding
authors.affiliation: Pacific Northwest National Laboratory -Marine Sciences Laboratory, 1529 West Sequim Bay Road, Sequim, WA 98382, USA.
authors.forename: Irvin R
authors.initials: IR
authors.lastname: Schultz
authors.affiliation: Northwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, 2725 Montlake Blvd E, Seattle, WA 98112, USA.
authors.forename: Denis A M
authors.initials: DA
authors.lastname: da Silva
authors.affiliation: Northwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, 2725 Montlake Blvd E, Seattle, WA 98112, USA.
authors.forename: Gina M
authors.initials: GM
authors.lastname: Ylitalo
authors.affiliation: Manchester Environmental Laboratory, United States Environmental Protection Agency Region 10, 7411 Beach Drive E, Port Orchard, WA 98366, USA.
authors.forename: Dave
authors.initials: D
authors.lastname: Ragsdale
authors.affiliation: Manchester Environmental Laboratory, United States Environmental Protection Agency Region 10, 7411 Beach Drive E, Port Orchard, WA 98366, USA.
authors.forename: Stephanie I
authors.initials: SI
authors.lastname: Harris
authors.affiliation: Manchester Environmental Laboratory, United States Environmental Protection Agency Region 10, 7411 Beach Drive E, Port Orchard, WA 98366, USA.
authors.forename: Stephanie
authors.initials: S
authors.lastname: Bailey
authors.affiliation: Manchester Environmental Laboratory, United States Environmental Protection Agency Region 10, 7411 Beach Drive E, Port Orchard, WA 98366, USA.
authors.forename: Barry V
authors.initials: BV
authors.lastname: Pepich
authors.affiliation: Northwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, 2725 Montlake Blvd E, Seattle, WA 98112, USA; Center for Reproductive Biology, Washington State University, Pullman, WA 98164, USA. Electronic address: penny.swanson@noaa.gov.
authors.forename: Penny
authors.initials: P
authors.lastname: Swanson
mesh_terms: D000818:Animals; D052244:Endocrine Disruptors / Q000633:toxicity*; D004997:Ethinyl Estradiol / Q000633:toxicity; D005260:Female; D005640:Follicle Stimulating Hormone / Q000235:genetics / Q000378:metabolism; D015870:Gene Expression / Q000187:drug effects; D006065:Gonadotropins, Pituitary / Q000235:genetics / Q000378:metabolism*; D007986:Luteinizing Hormone / Q000235:genetics / Q000378:metabolism; D017684:Oncorhynchus kisutch / Q000254:growth & development / Q000378:metabolism*; D010902:Pituitary Gland / Q000187:drug effects* / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D014204:Trenbolone Acetate / Q000633:toxicity; D014865:Waste Disposal, Fluid; D014874:Water Pollutants, Chemical / Q000633:toxicity*
chemical_list: D052244:Endocrine Disruptors; D006065:Gonadotropins, Pituitary; D012333:RNA, Messenger; D014874:Water Pollutants, Chemical; D004997:Ethinyl Estradiol; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone; D014204:Trenbolone Acetate
keywords: Endocrine disrupting compound; Follicle-stimulating hormone; Gonadotropin; Luteinizing hormone; Pituitary; Vitellogenin; Wastewater effluent