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Title
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Impaired swim bladder inflation in early life stage fathead minnows exposed to a deiodinase inhibitor, iopanoic acid
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Author
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Abstract
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| 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;36:29422952. 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. |
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Language
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English
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Source (journal)
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Environmental toxicology and chemistry. - New York, N.Y., 1982, currens
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Publication
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New York, N.Y.
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2017
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ISSN
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0730-7268
[print]
1552-8618
[online]
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DOI
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10.1002/ETC.3855
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Volume/pages
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36
:11
(2017)
, p. 2942-2952
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ISI
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000413923500009
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Pubmed ID
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28488362
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Full text (Publisher's DOI)
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Full text (open access)
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Full text (publisher's version - intranet only)
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