Contribution of maternal thyroxine to fetal thyroxine pools in normal rats near term

Journal Article · Tue May 01 00:00:00 EDT 1990 · Endocrinology; (USA)

DOI:https://doi.org/10.1210/endo-126-5-2765· OSTI ID:6774908

Morreale de Escobar, G; Calvo, R; Obregon, M J; Escobar Del Rey, F ^[1]

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1. Instituto de Investigaciones Biomedicas, Madrid (Spain)

Normal dams were equilibrated isotopically with ({sup 125}I)T4 infused from 11 to 21 days of gestation, at which time maternal and fetal extrathyroidal tissues were obtained to determine their ({sup 125}I)T4 and T4 contents. The specific activity of the ({sup 125}I)T4 in the fetal tissues was lower than in maternal T4 pools. The extent of this change allows evaluation of the net contribution of maternal T4 to the fetal extrathyroidal T4 pools. At 21 days of gestation, near term, this represents 17.5 +/- 0.9% of the T4 in fetal tissues, a value considerably higher than previously calculated. The methodological approach was validated in dams given a goitrogen to block fetal thyroid function. The specific activities of the ({sup 125}I)T4 in maternal and fetal T4 pools were then similar, confirming that in cases of fetal thyroid impairment the T4 in fetal tissues is determined by the maternal contribution. Thus, previous statements that in normal conditions fetal thyroid economy near term is totally independent of maternal thyroid status ought to be reconsidered.

• OSTI ID: 6774908
• Journal Information: Endocrinology; (USA), Vol. 126:5; ISSN 0013-7227
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
THYROID
BIOLOGICAL FUNCTIONS
THYROXINE
MEMBRANE TRANSPORT
FETUSES
IODINE 125
PLACENTA
PREGNANCY
RATS
TISSUE DISTRIBUTION
TRACER TECHNIQUES
AMINO ACIDS
ANIMALS
BETA DECAY RADIOISOTOPES
BODY
CARBOXYLIC ACIDS
DAYS LIVING RADIOISOTOPES
DISTRIBUTION
ELECTRON CAPTURE RADIOISOTOPES
ENDOCRINE GLANDS
FETAL MEMBRANES
FUNCTIONS
GLANDS
HORMONES
INTERMEDIATE MASS NUCLEI
IODINE ISOTOPES
ISOTOPE APPLICATIONS
ISOTOPES
MAMMALS
MEMBRANES
NUCLEI
ODD-EVEN NUCLEI
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
ORGANIC IODINE COMPOUNDS
ORGANS
PEPTIDE HORMONES
RADIOISOTOPES
RODENTS
THYROID HORMONES
VERTEBRATES
550201* - Biochemistry- Tracer Techniques