Journal ArticleDOI
Ontogeny of the pituitary‐thyroid system in fetal rats: Observations on the fetal thyroid after maternal treatment with goitrogen
TLDR
In fetal rats, the reciprocal relationship between the pituitary and the thyroid is established on approximately days 19–20 of gestation, which is based on changes in the weight and histology of the fetal thyroids.Abstract:
The critical time of onset of the reciprocal relationship between the pituitary and the thyroid in fetal rats was assessed by the appearance of goiters in fetuses after maternal treatment with goitrogen, propylthiouracil (PTU), on various days of gestation. The assessment was based on changes in the weight and histology of the fetal thyroids. The day following overnight mating was regarded as day 1 of gestation. Pregnant rats were treated with 40 mg PTU each day for two days and autopsied on the third day. The various experimental periods were days 16--18, 17--19, 18--20, 19--21, and 20--22. PTU given to pregnant rats on days 16 and 17 did not cause any change in the fetal thyroids. PTU given on days 17 and 18 caused only a slight increase of fetal "thyroid weight/body weight" ratio. In all other experimental periods (days 18--20, 19--21, and 20--22), PTU induced conspicuous goiters in fetuses, which was reflected by an increased weight of thyroids, an increased height of follicular cells, and a decreased amount of colloid stored in follicles. The results suggest that in fetal rats, the reciprocal relationship between the pituitary and the thyroid is established on approximately days 19--20 of gestation.read more
Citations
More filters
Journal ArticleDOI
Thyroid hormones and 5'-deiodinase in the rat fetus late in gestation: effects of maternal hypothyroidism.
Carmen Ruiz de Oña,Gabriella Morreale de Escobar,Rosa M. Calvo,Francisco Escobar del Rey,María Jesús Obregón +4 more
TL;DR: It is shown that near term, T4 and T3 concentrations in several tissues reach levels that are 50% or more of those described for adult animals, and that fetal thyroid function is influenced by maternal hypothyroidism.
Journal ArticleDOI
Predicting fetal perchlorate dose and inhibition of iodide kinetics during gestation: a physiologically-based pharmacokinetic analysis of perchlorate and iodide kinetics in the rat.
Rebecca A. Clewell,Elaine A. Merrill,Kyung O. Yu,Deirdre A. Mahle,Teresa R Sterner,David R. Mattie,Peter J Robinson,Jeffrey W. Fisher,Jeffery M. Gearhart +8 more
TL;DR: A comparison of model-predicted internal dosimetrics in the adult male, pregnant, and fetal rat indicates that the fetal thyroid is more sensitive to inhibition than that of the adult.
Journal ArticleDOI
Antithyroid drug-induced fetal goitrous hypothyroidism
TL;DR: The purpose of this Review is to clarify if and how fetal goitrous hypothyroidism can be prevented, and how to react when prevention has failed.
Journal ArticleDOI
Defective thyroid ontogenesis in fetal hypothyroid (hyt/hyt) mice
TL;DR: Thyroid glands of fetal hypothyroid (hyt/hyt) mice were studied to determine the effects of the mutant gene during embyrogenesis and the distribution of fetal mice into high or low iodine‐concentrating groups agreed closely with predicted frequencies for normal and mutant phenotypes.
Journal ArticleDOI
An interaction between thyroid hormone and nerve growth factor promotes the development of hippocampus, olfactory bulbs and cerebellum: a comparative biochemical study of normal and hypothyroid rats.
J. Clos,Ch. Legrand +1 more
TL;DR: The results clearly demonstrate that an interaction between T4 and NGF regulates the ontogeny of a number of neuronal structures in CNS independently of their neurotransmitter phenotype, but with a regional specificity.
References
More filters
Journal ArticleDOI
The mechanism of action of the thioureylene antithyroid drugs.
TL;DR: A scheme is proposed for the mechanism of inhibition by thioureylene drugs of TPO-catalyzed iodination of protein and tyrosine, which is capable of inhibiting their own and each other's metabolism.
Journal ArticleDOI
The irreversible inactivation of thyroid peroxidase by methylmercaptoimidazole, thiouracil, and propylthiouracil in vitro and its relationship to in vivo findings.
TL;DR: The findings suggest that the initial in vivo action of these drugs is to block iodination by trapping oxidized iodide, not by acting as "general inhibitors" of the TPO.
Journal ArticleDOI
Mechanism of Action of Thioureylene Antithyroid Drugs: Factors Affecting Intrathyroidal Metabolism of Propylthiouracil and Methimazole in Rats*
TL;DR: Results are similar to results previously reported for in vitro oxidation of PTU and MMI by the thyroid peroxidase system, and they offer support for the physiological significance of this scheme.
Journal ArticleDOI
Acute effects of hypothalamic ablation on plasma thyrotropin and prolactin concentrations in the suckling rat: evidence that early postnatal pituitary-thyroid regulation is independent of hypothalamic control.
Vladimir Strbak,Monte A. Greer +1 more
TL;DR: The data indicate that regulation of TSH secretion in the rat is independent of hypothalamic control until after the 5th postnatal day and is fully developed by day 12, which corresponds temporally with the postnatal rise of plasma TSH, T4, and T3 and hypothalamic TRH to adult concentrations and indicates maturation of the hypothalamic regulation ofTSH secretion.
Journal ArticleDOI
Effects of thyrotropin-releasing hormone (TRH) in maternal, fetal and newborn rats.
Akira Kojima,Jerome M. Hershman +1 more
TL;DR: The effects of synthetic TRH and methyl TRH in maternal, fetal and newborn rats were investigated andColloid droplet formation in the thyroid cell was enumerated as the index of thyroid hormone secretion induced by TSH.
Related Papers (5)
Evidence that control of fetal thyrotropin secretion is independent of both the fetal and maternal hypothalamus.
Nobuhiko Tonooka,Monte A. Greer +1 more
Influence of Thyroid Hormones on Enzyme Activities of Myelinating Rat Central‐Nervous Tissues
S.J. Wysocki,Wolfe Segal +1 more