title: Modulation of aromatase activity as a mode of action for endocrine disrupting chemicals in a marine fish.
abstract: The steroidogenic enzyme aromatase catalyzes the conversion of androgens to estrogens and therefore plays a central role in reproduction. In contrast to most vertebrates, teleost fish have two distinct forms of aromatase. Because brain aromatase activity in fish is up to 1000 times that in mammals, fish may be especially susceptible to negative effects from environmental endocrine-disrupting chemicals (EDCs) that impact aromatase activity. In this study, the effects of estradiol (E2), ethynylestradiol (EE2), octylphenol (OP), and androstatrienedione (ATD) on reproduction and aromatase activity in brains and gonads from the marine fish cunner (Tautogolabrus adspersus) was investigated. The purpose of the study was to explore the relationship between changes in aromatase activity and reproductive output in a marine fish, as well as compare aromatase activity to two commonly used indicators of EDC exposure, plasma vitellogenin (VTG) and gonadosomatic index (GSI). Results with E2, EE2, and ATD indicate that aromatase activity in cunner brain and ovary are affected differently by exposure to these EDCs. In the case of E2 and EE2, male brain aromatase activity was signficantly increased by these treatments, female brain aromatase activity was unaffected, and ovarian aromatase activity was significantly decreased. Treatment with the aromatase inhibitor ATD resulted in significantly decreased aromatase activity in male and female brain, but had no significant impact on ovarian aromatase activity. Regardless of test chemical, a decrease or an increase in male brain aromatase activity relative to controls was associated with decreased egg production in cunner and was also correlated with significant changes in GSI in both sexes. E2 and EE2 significantly elevated plasma VTG in males and females, while ATD had no significant effect. Treatment of cunner with OP had no significant effect on any measured endpoint. Overall, results with these exposures indicate EDCs that impact aromatase activity also affect reproductive output in spawning cunner.
authors.affiliation: United States Environmental Protection Agency, Office of Research and Development, National Health and Environmental Effects Research Laboratory, Atlantic Ecology Division, 27 Tarzwell Dr., Narragansett, RI 02882, United States. Electronic address: mills.lesley@epa.gov.
authors.forename: Lesley J
authors.initials: LJ
authors.lastname: Mills
authors.affiliation: United States Environmental Protection Agency, Office of Research and Development, National Health and Environmental Effects Research Laboratory, Atlantic Ecology Division, 27 Tarzwell Dr., Narragansett, RI 02882, United States.
authors.forename: Ruth E
authors.initials: RE
authors.lastname: Gutjahr-Gobell
authors.affiliation: United States Environmental Protection Agency, Office of Research and Development, National Health and Environmental Effects Research Laboratory, Atlantic Ecology Division, 27 Tarzwell Dr., Narragansett, RI 02882, United States.
authors.forename: Gerald E
authors.initials: GE
authors.lastname: Zaroogian
authors.affiliation: United States Environmental Protection Agency, Office of Research and Development, National Health and Environmental Effects Research Laboratory, Atlantic Ecology Division, 27 Tarzwell Dr., Narragansett, RI 02882, United States.
authors.forename: Doranne Borsay
authors.initials: DB
authors.lastname: Horowitz
authors.affiliation: United States Environmental Protection Agency, Office of Research and Development, National Health and Environmental Effects Research Laboratory, Toxicity Assessment Division, Research Triangle Park, NC 27711, United States.
authors.forename: Susan C
authors.initials: SC
authors.lastname: Laws
mesh_terms: D000818:Animals; D001141:Aromatase / Q000378:metabolism*; D001921:Brain / Q000187:drug effects; D052244:Endocrine Disruptors / Q000633:toxicity*; D004789:Enzyme Activation / Q000187:drug effects; D005260:Female; D008297:Male; D010058:Oviposition / Q000187:drug effects; D010473:Perciformes / Q000502:physiology*; D014819:Vitellogenins / Q000097:blood; D014874:Water Pollutants, Chemical / Q000633:toxicity*
chemical_list: D052244:Endocrine Disruptors; D014819:Vitellogenins; D014874:Water Pollutants, Chemical; D001141:Aromatase
keywords: Aromatase; EDCs; Endocrine disruption; Fish; Reproduction