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Dietary exposure to 2,2´,4,4´-Tetrabromodiphenyl Ether (PBDE-47) alters thyroid status and thyroid hormone–regulated gene transcription in the pituitary and brain

UNCW Author/Contributor (non-UNCW co-authors, if there are any, appear on document)
Sean C. Lema, Assistant Professor (Creator)
Institution
The University of North Carolina Wilmington (UNCW )
Web Site: http://library.uncw.edu/

Abstract: BACKGROUND: Polybrominated diphenyl ether (PBDE) flame retardants have been implicated as disruptors of the hypothalamic-pituitary-thyroid axis. Animals exposed to PBDEs may show reduced plasma thyroid hormone (TH), but it is not known whether PBDEs impact TH-regulated pathways in target tissues. OBJECTIVE: We examined the effects of dietary exposure to 2,2´,4,4´-tetrabromodiphenyl ether (PBDE-47)—commonly the highest concentrated PBDE in human tissues—on plasma TH levels and on gene transcripts for glycoprotein hormone a-subunit (GPHa) and thyrotropin ß-subunit (TSHß) in the pituitary gland, the autoinduced TH receptors a and ß in the brain and liver, and the TH-responsive transcription factor basic transcription element-binding protein (BTEB) in the brain. METHODS: Breeding pairs of adult fathead minnows (Pimephales promelas) were given dietary PBDE-47 at two doses (2.4 µg/pair/day or 12.3 µg/pair/day) for 21 days. RESULTS: Minnows exposed to PBDE-47 had depressed plasma thyroxine (T4), but not 3,5,3´-triiodothyronine (T3). This decline in T4 was accompanied by elevated mRNA levels for TSHß (low dose only) in the pituitary. PBDE-47 intake elevated transcript for TH receptor a in the brain of females and decreased mRNA for TH receptor ß in the brain of both sexes, without altering these transcripts in the liver. In males, PBDE-47 exposure also reduced brain transcripts for BTEB. CONCLUSIONS: Our results indicate that dietary exposure to PBDE-47 alters TH signaling at multiple levels of the hypothalamic-pituitary-thyroid axis and provide evidence that TH-responsive pathways in the brain may be particularly sensitive to disruption by PBDE flame retardants. KEY WORDS: basic transcription element-binding protein, brain, endocrine disruption, PBDE-47, polybrominated diphenyl ethers, thyroid hormone, thyroid hormone receptor, thyroid-stimulating hormone, thyrotropin. Environ Health Perspect 116:1694–1699 (2008). doi:10.1289/ehp.11570 available via http://dx.doi.org/ [Online 1 August 2008]

Additional Information

Publication
Lema, S. C., Dickey, J. T., Schultz, I. R., & Swanson, P. (2008). Dietary exposure to 2,2´,4,4´-Tetrabromodiphenyl Ether (PBDE-47) alters thyroid status and thyroid hormone–regulated gene transcription in the pituitary and brain. Environmental Health Perspectives, 116, 1694–1699. doi:10.1289/ehp.11570. Reproduced with permission from Environmental Health Perspectives.
Language: English
Date: 2009
Keywords
Endocrine disrupting chemicals, Polybrominated diphenyl ethers, Thyroid hormones, Thyrotropin
Subjects
Polybrominated diphenyl ethers
Thyroid hormones
Thyrotropin
Endocrine disrupting chemicals