HOME HELP CONTACT US SUBSCRIPTIONS ARCHIVE SEARCH		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Accepted manuscript (PDF) All Versions of this Article: JOE-08-0472v1 202/1/43    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Lema, S. Articles by Swanson, P. Search for Related Content PubMed PubMed Citation Articles by Lema, S. Articles by Swanson, P.

S Lema, Biology and Marine Biology, University of North Carolina Wilmington, Wilmington, 28403, United States
J Dickey, School of Aquatic and Fishery Sciences, University of Washington, Seattle, United States
I Schultz, Marine Sciences Laboratory, Battelle, Sequim , United States
P Swanson, Physiology Program, Northwest Fisheries Science Center, NOAA Fisheries, 98382, United States

Correspondence: Sean Lema, Email: lemas{at}uncw.edu

Thyroid hormones regulate growth, morphological development and migratory behaviors in teleost fish, yet little is known about the transcriptional dynamics of gene targets for thyroid hormones in these taxa. Here, we characterized thyroid hormone regulation of mRNAs encoding thyrotropin subunits and thyroid hormone receptors in an adult teleost fish model, the fathead minnow (Pimephales promelas). Breeding pairs of adult minnows were fed diets containing 3,5,3'-triiodo-L-thyronine (T3) or the goitrogen methimazole for 10 days. In males and females, dietary intake of exogenous T3 elevated circulating total T3, while methimazole depressed plasma levels of total thyroxine (T4). In both sexes, this methimazole-induced reduction in T4 led to elevated mRNA abundance for thyroid-stimulating hormone β-subunit (tshβ) in the pituitary gland. Fish treated with T3 had elevated transcript levels for thyroid hormone receptor isoforms and β (tr and trβ) in the liver and brain, but reduced levels of brain mRNA for the immediate-early gene basic transcription factor-binding protein (bteb). In the ovary and testis, exogenous T3 elevated gene transcripts for tshβ, glycoprotein hormone -subunit (gph) and trβ, while not affecting tr levels. Taken together, these results demonstrate negative feedback of T4 on pituitary tshβ, identify tr and trβ as T3-autoinduced genes in the brain and liver, and provide new evidence that tshβ, gph and trβ are thyroid hormone-regulated in the gonad of teleosts. Adult teleost models are increasingly used to evaluate the endocrine-disrupting effects of chemical contaminants, and our results provide a systemic assessment of thyroid hormone-responsive genes during that life stage.