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

This Article Full Text Full Text (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. C Articles by Swanson, P. Search for Related Content PubMed PubMed Citation Articles by Lema, S. C Articles by Swanson, P.

Physiology Program, Northwest Fisheries Science Center, NOAA Fisheries, Seattle, Washington 98112, USA
¹ School of Aquatic and Fishery Sciences, University of Washington, Seattle, Washington 98195, USA
² Pacific Northwest Division, Battelle, Marine Sciences Laboratory, Sequim, Washington 98382, USA

(Correspondence should be addressed to S C Lema who is now at Department of Biology and Marine Biology, Center for Marine Science, University of North Carolina, Wilmington, 601 South College Road, Wilmington, North Carolina 28403, USA; Email: lemas{at}uncw.edu)

Thyroid hormones (THs) regulate growth, morphological development, and migratory behaviors in teleost fish, yet little is known about the transcriptional dynamics of gene targets for THs in these taxa. Here, we characterized TH regulation of mRNAs encoding thyrotropin subunits and thyroid hormone receptors (TRs) 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 thyrotropin β-subunit (tshβ) in the pituitary gland. Fish treated with T₃ had elevated transcript levels for TR 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 THs 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 TH-responsive genes during that life stage.