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Role of thyroid hormone during early brain development
Gabriella Morreale de Escobar1, María Jesús Obregon, Francisco Escobar del Rey
1Instituto de Investigaciones Biomedicas Alberto Sols, Consejo Superior de Investigaciones Cientificas (CSIC) y Universidad Autonoma de Madrid (UAM), Arturo Duperier, 4, 28029-Madrid, Spain. gmorreale@iib.uam.es
European Journal of Endocrinology
|November 24, 2004
Summary
Maternal thyroid hormone (T4) is crucial for fetal brain development, especially before midgestation. Insufficient T4 (hypothyroxinemia) can harm neurodevelopment, but iodine supplementation may prevent learning disabilities.
Area of Science:
- Neuroscience
- Endocrinology
- Developmental Biology
Background:
- Maternal thyroid hormone is essential for fetal brain development.
- Maternal hypothyroxinemia, low thyroxine (T4) levels during pregnancy, poses risks to fetal neurodevelopment.
- The mother is the primary source of T4 for the developing fetal brain before midgestation.
Purpose of the Study:
- To review the role of maternal thyroid hormone in early human fetal brain development.
- To highlight the critical importance of maternal thyroxine (T4) for fetal neurodevelopment.
- To discuss the implications of maternal hypothyroxinemia and iodine deficiency.
Main Methods:
- Review of existing literature on maternal thyroid hormone and fetal brain development.
- Analysis of data on thyroxine (T4) and triiodothyronine (T3) transfer and metabolism in the fetal compartment.
- Consideration of experimental evidence from rat models.
Main Results:
- Maternal thyroxine (T4) crosses the placenta, with free T4 (FT4) reaching biologically significant levels in fetal fluids.
- Local conversion of T4 to T3 in the fetal cerebral cortex achieves adult concentrations by midgestation.
- Thyroid hormone is vital for corticogenesis early in pregnancy, as supported by rat studies.
Conclusions:
- The surge in maternal free thyroxine (FT4) in the first trimester is critical for fetal T3 generation and brain development.
- Maternal hypothyroxinemia, often caused by iodine deficiency, increases the risk of neurological disabilities in children.
- Iodine supplementation for pregnant women can prevent learning disabilities linked to maternal thyroid hormone deficiency.