Document Detail

Differential effects of maternal dexamethasone treatment on circulating thyroid hormone concentrations and tissue deiodinase activity in the pregnant ewe and fetus.
MedLine Citation:
PMID:  17110425     Owner:  NLM     Status:  MEDLINE    
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.
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:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2006-11-16
Journal Detail:
Title:  Endocrinology     Volume:  148     ISSN:  0013-7227     ISO Abbreviation:  Endocrinology     Publication Date:  2007 Feb 
Date Detail:
Created Date:  2007-01-17     Completed Date:  2007-02-27     Revised Date:  2014-10-14    
Medline Journal Info:
Nlm Unique ID:  0375040     Medline TA:  Endocrinology     Country:  United States    
Other Details:
Languages:  eng     Pagination:  800-5     Citation Subset:  AIM; IM    
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MeSH Terms
Dexamethasone / pharmacology*
Fetal Blood*
Fetus / enzymology*
Glucocorticoids / pharmacology*
Iodide Peroxidase / metabolism*
Kidney / embryology
Liver / embryology
Osmolar Concentration
Placenta / enzymology
Pregnancy, Animal / blood,  drug effects,  metabolism*
Thyroid Hormones / blood*
Thyroxine / blood
Triiodothyronine / blood
Grant Support
S18103//Biotechnology and Biological Sciences Research Council
Reg. No./Substance:
0/Glucocorticoids; 0/Thyroid Hormones; 06LU7C9H1V/Triiodothyronine; 7S5I7G3JQL/Dexamethasone; EC Peroxidase; Q51BO43MG4/Thyroxine

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