title: Development of the Larval Amphibian Growth and Development Assay: effects of chronic 4-tert-octylphenol or 17β-trenbolone exposure in Xenopus laevis from embryo to juvenile.
abstract: The Larval Amphibian Growth and Development Assay (LAGDA) is a globally harmonized test guideline developed by the U.S. Environmental Protection Agency in collaboration with Japan's Ministry of the Environment. The LAGDA was designed to evaluate apical effects of chronic chemical exposure on growth, thyroid-mediated amphibian metamorphosis and reproductive development. During the validation phase, two well-characterized endocrine-disrupting chemicals were tested to evaluate the performance of the initial assay design: xenoestrogen 4-tert-octylphenol (tOP) and xenoandrogen 17β-trenbolone (TB). Xenopus laevis embryos were exposed, in flow-through conditions, to tOP (nominal concentrations: 0.0, 6.25, 12.5, 25 and 50 µg l-1) or TB (nominal concentrations: 0.0, 12.5, 25, 50 and 100 ng l-1) until 8 weeks post-metamorphosis, at which time growth measurements were taken, and histopathology assessments were made of the gonads, reproductive ducts, liver and kidneys. There were no effects on growth in either study and no signs of overt toxicity, sex reversal or gonad dysgenesis. Exposure to tOP caused a treatment-related decrease in circulating thyroxine and an increase in thyroid follicular cell hypertrophy and hyperplasia (25 and 50 µg l-1) during metamorphosis. Müllerian duct development was affected after exposure to both chemicals; tOP exposure caused dose-dependent maturation of oviducts in both male and female frogs, whereas TB exposure caused accelerated Müllerian duct regression in males and complete regression in >50% of the females in the 100 ng l-1treatment. Based on these results, the LAGDA performed adequately to evaluate apical effects of chronic exposure to two endocrine-active compounds and is the first standardized amphibian multiple life stage toxicity test to date. Published 2016. This article is a U.S. Government work and is in the public domain in the USA.
authors.affiliation: US EPA Mid-Continent Ecology Division, 6201 Congdon Blvd, Duluth, MN, 55804, USA. haselman.jon@epa.gov.
authors.forename: Jonathan T
authors.initials: JT
authors.lastname: Haselman
authors.affiliation: US EPA Mid-Continent Ecology Division, 6201 Congdon Blvd, Duluth, MN, 55804, USA.
authors.forename: Patricia A
authors.initials: PA
authors.lastname: Kosian
authors.affiliation: US EPA Mid-Continent Ecology Division, 6201 Congdon Blvd, Duluth, MN, 55804, USA.
authors.forename: Joseph J
authors.initials: JJ
authors.lastname: Korte
authors.affiliation: US EPA Mid-Continent Ecology Division, 6201 Congdon Blvd, Duluth, MN, 55804, USA.
authors.forename: Allen W
authors.initials: AW
authors.lastname: Olmstead
authors.affiliation: Okazaki Institute for Integrative Bioscience, National Institute for Basic Biology, National Institutes of Natural Sciences, 5-1 Higashiyama, Myodaiji, Okazaki, Aichi, 444-8787, Japan.
authors.forename: Taisen
authors.initials: T
authors.lastname: Iguchi
authors.affiliation: US EPA Mid-Continent Ecology Division, 6201 Congdon Blvd, Duluth, MN, 55804, USA.
authors.forename: Rodney D
authors.initials: RD
authors.lastname: Johnson
authors.affiliation: US EPA Mid-Continent Ecology Division, 6201 Congdon Blvd, Duluth, MN, 55804, USA.
authors.forename: Sigmund J
authors.initials: SJ
authors.lastname: Degitz
mesh_terms: D000818:Animals; D001681:Biological Assay; D004305:Dose-Response Relationship, Drug; D004625:Embryo, Nonmammalian / Q000187:drug effects*; D052244:Endocrine Disruptors / Q000633:toxicity*; D004784:Environmental Monitoring / Q000379:methods*; D005260:Female; D007814:Larva; D008297:Male; D008675:Metamorphosis, Biological / Q000187:drug effects*; D009095:Mullerian Ducts / Q000187:drug effects / Q000196:embryology / Q000254:growth & development; D010636:Phenols / Q000633:toxicity*; D013961:Thyroid Gland / Q000187:drug effects / Q000196:embryology / Q000254:growth & development; D014204:Trenbolone Acetate / Q000633:toxicity*; D014982:Xenopus laevis
chemical_list: D052244:Endocrine Disruptors; D010636:Phenols; C105260:4-tert-octylphenol; D014204:Trenbolone Acetate
keywords: 17β-trenbolone; 4-tert-octylphenol; OCSPP 890.2300; OECD Test 241; Xenopus laevis; endocrine-disrupting chemicals; reproductive development; thyroid