Thyroid hormone relationships in the fetal and newborn lamb

Plasma thyroxine (T4) and reverse triiodothyronine (rT3) concentrations have been measured in chronically catheterised sheep fetuses during the last third of gestation. In some animals T4 and rT3 concentrations fell before delivery but there was no change in the t4/rT3 ratio. In several serially sam...

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Bibliographic Details
Published inBiology of the neonate Vol. 37; no. 3/4; pp. 138 - 144
Main Authors Mathur, H, Brown, B.L, Krane, E.J, Thomas, A.L, Nathanielsz, P.W
Format Journal Article
LanguageEnglish
Published Switzerland 01.01.1980
Subjects
animal reproduction
Animals
Animals, Newborn - blood
Female
Fetal Blood - analysis
Gestational Age
Hydrocortisone - administration & dosage
Hydrocortisone - pharmacology
Labor, Obstetric - drug effects
Pregnancy
Progesterone - pharmacology
Sheep - blood
Thyroxine - blood
Triiodothyronine - blood
Triiodothyronine, Reverse - blood
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Summary:Plasma thyroxine (T4) and reverse triiodothyronine (rT3) concentrations have been measured in chronically catheterised sheep fetuses during the last third of gestation. In some animals T4 and rT3 concentrations fell before delivery but there was no change in the t4/rT3 ratio. In several serially sampled fetuses a small rise in plasma triiodothyronine concentration has been demonstrated in the days preceding delivery. Infusion of cortisol to fetuses commencing at 130 days of gestation (term 147 days) with the simultaneous administration of progesterone to delay labour resulted in changes in T4 and rT3 concentrations which were similar to those normally seen at term. The nature of the changes in the peripheral metabolism of T4 around the time of birth are discussed.
ISSN:0006-3126
1421-9727
DOI:10.1159/000241265