Endocrinology, Vol 114, 305-307, Copyright © 1984 by Endocrine Society

ARTICLES

L-thyroxine and 3,5,3'-triiodo-L-thyronine in rat embryos before onset of fetal thyroid function

MJ Obregon, J Mallol, R Pastor, G Morreale de Escobar and F Escobar del Rey

T4 and T3 have been measured by RIA in 10-12-day-old rat embryo- trophoblasts, and in 13-20-day-old embryos and placentas, as well as in a few samples of amniotic fluid. Both T4 and T3 were measured after extraction of the samples with ethanol, purification by paper chromatography, anion exchange resin, or both. T4 and T3 could be shown in all samples studied. The amounts of T4 and T3 per conceptus and their concentrations were higher in embryo-trophoblasts and placentas than in 13-18-day-old embryos. The concentrations of T4 and T3 remained fairly constant in the embryos until day 19, when they appeared to increase. The molar ratios of T4 to T3 were 1.4, 8.5 and 103 for embryos, placentas and maternal plasma, respectively. These data show that, for at least one mammalian species, embryonic tissues are provided with T4 and T3 from the earliest date studied, namely 4 days after uterine implantation, and well before onset of thyroid function, which in the rat starts after 17 days gestational age. Such a result suggests that statements denying a possible role of thyroid hormones in early embryogenesis ought to be reconsidered.

This article has been cited by other articles:

				B. R. Noble, R. P. Babiuk, R. D. Clugston, T. M. Underhill, H. Sun, R. Kawaguchi, P. G. Walfish, R. Blomhoff, T. E. Gundersen, and J. J. Greer Mechanisms of action of the congenital diaphragmatic hernia-inducing teratogen nitrofen Am J Physiol Lung Cell Mol Physiol, October 1, 2007; 293(4): L1079 - L1087. [Abstract] [Full Text] [PDF]

				F. Vermiglio, V. P. Lo Presti, M. Moleti, M. Sidoti, G. Tortorella, G. Scaffidi, M. G. Castagna, F. Mattina, M. A. Violi, A. Crisa, et al. Attention Deficit and Hyperactivity Disorders in the Offspring of Mothers Exposed to Mild-Moderate Iodine Deficiency: A Possible Novel Iodine Deficiency Disorder in Developed Countries J. Clin. Endocrinol. Metab., December 1, 2004; 89(12): 6054 - 6060. [Abstract] [Full Text] [PDF]

				L Quignodon, C Legrand, N Allioli, A Guadano-Ferraz, J Bernal, J Samarut, and F Flamant Thyroid hormone signaling is highly heterogeneous during pre- and postnatal brain development J. Mol. Endocrinol., October 1, 2004; 33(2): 467 - 476. [Abstract] [Full Text] [PDF]

				I. A. T. M. Meerts, Y. Assink, P. H. Cenijn, J. H. J. van den Berg, B. M. Weijers, A. Bergman, J. H. Koeman, and A. Brouwer Placental Transfer of a Hydroxylated Polychlorinated Biphenyl and Effects on Fetal and Maternal Thyroid Hormone Homeostasis in the Rat Toxicol. Sci., August 1, 2002; 68(2): 361 - 371. [Abstract] [Full Text] [PDF]

				F. R. S. Lima, A. Gervais, C. Colin, M. Izembart, V. M. Neto, and M. Mallat Regulation of Microglial Development: A Novel Role for Thyroid Hormone J. Neurosci., March 15, 2001; 21(6): 2028 - 2038. [Abstract] [Full Text] [PDF]

				A. L. S. Dowling, E. A. Iannacone, and R. T. Zoeller Maternal Hypothyroidism Selectively Affects the Expression of Neuroendocrine-Specific Protein A Messenger Ribonucleic Acid in the Proliferative Zone of the Fetal Rat Brain Cortex Endocrinology, January 1, 2001; 142(1): 390 - 399. [Abstract] [Full Text] [PDF]

				G. Morreale de Escobar, M. Jesús Obregón, and F. Escobar del Rey Is Neuropsychological Development Related to Maternal Hypothyroidism or to Maternal Hypothyroxinemia? J. Clin. Endocrinol. Metab., November 1, 2000; 85(11): 3975 - 3987. [Abstract] [Full Text]

				A. L. S. Dowling, G. U. Martz, J. L. Leonard, and R. T. Zoeller Acute Changes in Maternal Thyroid Hormone Induce Rapid and Transient Changes in Gene Expression in Fetal Rat Brain J. Neurosci., March 15, 2000; 20(6): 2255 - 2265. [Abstract] [Full Text] [PDF]

				J. M. Bates, D. L. St. Germain, and V. A. Galton Expression Profiles of the Three Iodothyronine Deiodinases, D1, D2, and D3, in the Developing Rat Endocrinology, February 1, 1999; 140(2): 844 - 851. [Abstract] [Full Text]

				J. P. Schroder-van der Elst, D. van der Heide, G. Morreale de Escobar, and M. J. Obregon Iodothyronine Deiodinase Activities in Fetal Rat Tissues at Several Levels of Iodine Deficiency: A Role for the Skin in 3,5,3'-Triiodothyronine Economy? Endocrinology, May 1, 1998; 139(5): 2229 - 2234. [Abstract] [Full Text] [PDF]

				J. P. S.-V. D. Elst, D. Van Der Heide, H. Rokos, G. M. De Escobar, and J. Kohrle Synthetic flavonoids cross the placenta in the rat and are found in fetal brain Am J Physiol Endocrinol Metab, February 1, 1998; 274(2): E253 - E256. [Abstract] [Full Text] [PDF]

				J. H. Oppenheimer and H. L. Schwartz Molecular Basis of Thyroid Hormone-Dependent Brain Development Endocr. Rev., August 1, 1997; 18(4): 462 - 475. [Abstract] [Full Text] [PDF]

				H. L. Schwartz, M. E. Ross, and J. H. Oppenheimer Lack of Effect of Thyroid Hormone on Late Fetal Rat Brain Development Endocrinology, August 1, 1997; 138(8): 3119 - 3124. [Abstract] [Full Text] [PDF]

				P. A. Piosik, M. van Groenigen, J. van Doorn, F. Baas, and J. J. M. de Vijlder Effects of Maternal Thyroid Status on Thyroid Hormones and Growth in Congenitally Hypothyroid Goat Fetuses during the Second Half of Gestation Endocrinology, January 1, 1997; 138(1): 5 - 11. [Abstract] [Full Text] [PDF]

				C. Guerra, C. Roncero, A. Porras, M. Fernández, and M. Benito Triiodothyronine Induces the Transcription of the Uncoupling Protein Gene and Stabilizes Its mRNA in Fetal Rat Brown Adipocyte Primary Cultures J. Biol. Chem., January 26, 1996; 271(4): 2076 - 2081. [Abstract] [Full Text] [PDF]

				G. N. Burrow, D. A. Fisher, and P. R. Larsen Maternal and Fetal Thyroid Function N. Engl. J. Med., October 20, 1994; 331(16): 1072 - 1078. [Full Text]