| Differential effects of maternal dexamethasone treatment on circulating thyroid hormone concentrations and tissue deiodinase activity in the pregnant ewe and fetus. | |
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MedLine Citation:
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PMID: 17110425 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Clinically, treatment of pregnant women at risk of preterm delivery with synthetic glucocorticoids accelerates fetal maturation. This study investigated the effect of maternal dexamethasone treatment, in clinically relevant doses, on plasma thyroid hormone concentrations and tissue deiodinase activities (D1, D2, and D3) in ewes and their fetuses. From 125 d of gestation (term 145 +/- 2 d), pregnant ewes were injected twice im with either saline (2 ml of 0.9% NaCl, n = 11) or dexamethasone (2 x 12 mg in 2 ml of saline, n = 10) at 24-h intervals. Maternal dexamethasone treatment increased plasma T(3) and reverse T(3) (rT(3)), but not T(4), concentrations in the fetuses. In the dexamethasone-exposed fetuses, hepatic D1 activity was higher, and renal and placental D3 activities were lower, than in the saline-exposed fetuses. In the ewes, plasma concentrations of T(3) and T(4) were reduced, and rT(3) increased, by dexamethasone treatment without any change in tissue deiodinase activity. Therefore, maternal dexamethasone treatment has different effects on the thyroid hormone axis of the pregnant ewe and fetus. In the fetus, the dexamethasone-induced rise in circulating T(3) may be due to both increased hepatic production of T(3) from T(4), and reduced clearance of T(3) by the kidney and placenta. Changes in T(3) bioavailability may mediate some of the maturational effects of antenatal glucocorticoid treatment in the preterm fetus. |
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Authors:
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Alison J Forhead; Juanita K Jellyman; David S Gardner; Dino A Giussani; Ellen Kaptein; Theo J Visser; Abigail L Fowden |
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Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't Date: 2006-11-16 |
Journal Detail:
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Title: Endocrinology Volume: 148 ISSN: 0013-7227 ISO Abbreviation: Endocrinology Publication Date: 2007 Feb |
Date Detail:
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Created Date: 2007-01-17 Completed Date: 2007-02-27 Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 0375040 Medline TA: Endocrinology Country: United States |
Other Details:
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Languages: eng Pagination: 800-5 Citation Subset: AIM; IM |
Affiliation:
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Department of Physiology, Development and Neuroscience, University of Cambridge, Downing Street, Cambridge CB2 3EG, United Kingdom. ajf1005@cam.ac.uk |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Animals Dexamethasone / pharmacology* Female Fetal Blood* Fetus / enzymology* Glucocorticoids / pharmacology* Iodide Peroxidase / metabolism* Kidney / embryology Liver / embryology Osmolar Concentration Placenta / enzymology Pregnancy Pregnancy, Animal / blood, drug effects, metabolism* Sheep Thyroid Hormones / blood* Thyroxine / blood Triiodothyronine / blood |
| Chemical | |
Reg. No./Substance:
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0/Glucocorticoids; 0/Thyroid Hormones; 50-02-2/Dexamethasone; 6893-02-3/Triiodothyronine; 7488-70-2/Thyroxine; EC 1.11.1.8/Iodide Peroxidase |
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