Impaired swim bladder inflation in early life stage fathead minnows exposed to a deiodinase inhibitor, iopanoic acid

Jenna E. Cavallin, Gerald T. Ankley, Brett R. Blackwell, Chad A. Blanksma, Kellie A. Fay, Kathleen M. Jensen, Michael D. Kahl, Dries Knapen, Patricia A. Kosian, Shane T. Poole, Eric C. Randolph, Anthony L. Schroeder, Lucia Vergauwen, Daniel L. Villeneuve

    Research output: Contribution to journalArticlepeer-review

    6 Scopus citations


    Inflation of the posterior and/or anterior swim bladder is a process previously demonstrated to be regulated by thyroid hormones. We investigated whether inhibition of deiodinases, which convert thyroxine (T4) to the more biologically active form, 3,5,3′-triiodothyronine (T3), would impact swim bladder inflation. Two experiments were conducted using a model deiodinase inhibitor, iopanoic acid (IOP). First, fathead minnow embryos were exposed to 0.6, 1.9, or 6.0 mg/L or control water until 6 d postfertilization (dpf), at which time posterior swim bladder inflation was assessed. To examine anterior swim bladder inflation, a second study was conducted with 6-dpf larvae exposed to the same IOP concentrations until 21 dpf. Fish from both studies were sampled for T4/T3 measurements and gene transcription analyses. Incidence and length of inflated posterior swim bladders were significantly reduced in the 6.0 mg/L treatment at 6 dpf. Incidence of inflation and length of anterior swim bladder were significantly reduced in all IOP treatments at 14 dpf, but inflation recovered by 18 dpf. Throughout the larval study, whole-body T4 concentrations increased and T3 concentrations decreased in all IOP treatments. Consistent with hypothesized compensatory responses, deiodinase-2 messenger ribonucleic acid (mRNA) was up-regulated in the larval study, and thyroperoxidase mRNA was down-regulated in all IOP treatments in both studies. These results support the hypothesized adverse outcome pathways linking inhibition of deiodinase activity to impaired swim bladder inflation. Environ Toxicol Chem 2017;36:2942–2952. Published 2017 Wiley Periodicals Inc. on behalf of SETAC. This article is a US government work and, as such, is in the public domain in the United States of America.

    Original languageEnglish (US)
    Pages (from-to)2942-2952
    Number of pages11
    JournalEnvironmental Toxicology and Chemistry
    Issue number11
    StatePublished - Nov 2017


    • Adverse outcome pathway
    • Aquatic toxicology
    • Developmental toxicity
    • Endocrine-disrupting compounds
    • Thyroid disruption

    Fingerprint Dive into the research topics of 'Impaired swim bladder inflation in early life stage fathead minnows exposed to a deiodinase inhibitor, iopanoic acid'. Together they form a unique fingerprint.

    Cite this