Development of a short-term reproductive endocrine bioassay using steroid hormone and vitellogenin end points in the estuarine mummichog (Fundulus heteroclitus).
We have developed a short-term gonadal recrudescence test with the estuarine mummichog (Fundulus heteroclitus) and determined endocrine end points sensitive to a strong estrogen agonist (ethynylestradiol; EE2) and an antiestrogen (ZM 189,154; ZM) at concentrations of 0 to 1,000 ng/L in three separate experiments. A protocol was developed to ensure a year-round supply of recrudescing fish. A protocol for determining steroid production (testosterone and 11-ketotestosterone [11-KT] in incubated testes tissue and testosterone and 17-estradiol [E2] in incubated prematurational follicles) was optimized. Recrudescing fish (males, gonadosomatic index = 2%; females = 10%) were exposed to graded doses of EE2 or ZM for 7 to 15 d using a static daily-renewal protocol. At high EE2 (>250 ng/L), the effect on males was depression of androgen steroidogenesis and plasma steroid levels. In females, high EE2 depressed gonadal production and circulating E2 levels; however, EE2 concentrations <100 ng/L caused increased gonadal production and plasma E2. Low ZM (<100 ng/L) had little effect on male and female fish, while higher concentrations (>250 ng/L) increased E2 and 11-KT production while decreasing plasma 11-KT and E2 (1,000 ng/L only). Male and female plasma vitellogenin responded in a concentration-dependent fashion to EE2 with no effect by ZM. The low observable effect concentrations for the endocrine parameters were 1 ng/L for EE2 and 250 ng/L for ZM. The bioassay and results encompassing the environmentally relevant exposure range (1-100 ng/L) will be useful for assessing effects of endocrine-active contaminants in estuarine environments.
MacLatchy
Deborah L
DL
Department of Biology and Canadian Rivers Institute, University of New Brunswick, Saint John, New Brunswick E2L 4L5, Canada. maclatch@unbsj.ca
Courtenay
Simon C
SC
Rice
Charles D
CD
Van der Kraak
Glen J
GJ
D000818:Animals; D001681:Biological Assay / Q000379:methods*; D004305:Dose-Response Relationship, Drug; D004781:Environmental Exposure / Q000032:analysis; D004958:Estradiol / Q000096:biosynthesis* / Q000097:blood; D004997:Ethinyl Estradiol / Q000494:pharmacology; D005260:Female; D023781:Fundulidae / Q000378:metabolism*; D008297:Male; D009929:Organ Size; D010053:Ovary / Q000187:drug effects / Q000378:metabolism; D012044:Regression Analysis; D013737:Testis / Q000187:drug effects / Q000378:metabolism; D013739:Testosterone / Q000031:analogs & derivatives / Q000096:biosynthesis* / Q000097:blood; D013764:Tetrahydronaphthalenes / Q000494:pharmacology; D013997:Time Factors; D014819:Vitellogenins / Q000097:blood*; D014874:Water Pollutants, Chemical / Q000633:toxicity; D005466:Fluorocarbons
D004958:Estradiol; D004997:Ethinyl Estradiol; D013739:Testosterone; D013764:Tetrahydronaphthalenes; D014819:Vitellogenins; D014874:Water Pollutants, Chemical; C088608:ZM 189154; D005466:Fluorocarbons