• Abstract
  • Introduction
  • Ontogenesis of Thyroid Hormone Action in Fetal Development
  • Deiodination of Thyroid Hormones
  • Thyroid Hormone Transporters in the Brain
  • Tr Genes and Activity
  • Conclusion
  • Declaration of Interest
  • Funding
  • References

رئوس مطالب

  • چکیده
  • مقدمه
  • انتوژنی عملکرد هورمون تیروئیدی در طول تکامل جنین
  • دی یدیناسیون هورمون‌های تیروئیدی
  • ناقل‌های هورمون تیروئید در مغز
  • ژن‌های TR و عملکرد آن‌ها
  • نتیجه گیری


The development of fetal thyroid function is dependent on the embryogenesis, differentiation, and maturation of the thyroid gland. This is coupled with evolution of the hypothalamic-pituitary-thyroid axis and thyroid hormone metabolism, resulting in the regulation of thyroid hormone action, production, and secretion. Throughout gestation there is a steady supply of maternal thyroxine (T(4)) which has been observed in embryonic circulation as early as 4 weeks post-implantation. This is essential for normal early fetal neurogenesis. Triiodothyronine concentrations remain very low during gestation due to metabolism via placental and fetal deiodinase type 3. T(4) concentrations are highly regulated to maintain low concentrations, essential for protecting the fetus and reaching key neurological sites such as the cerebral cortex at specific developmental stages. There are many known cell membrane thyroid hormone transporters in fetal brain that play an essential role in regulating thyroid hormone concentrations in key structures. They also provide the route for intracellular thyroid hormone interaction with associated thyroid hormone receptors, which activate their action. There is a growing body of experimental evidence from rats and humans to suggest that even mild maternal hypothyroxinemia may lead to abnormalities in fetal neurological development. Our review will focus on the ontogeny of thyroid hormone in fetal development, with a focus on cell membrane transporters and TR action in the brain.


Our understanding of the complex processes involved in ensuring normal fetal development is increasing. Knowledge of the key relationships between thyroid hormone and brain development has progressed significantly over the past decade. However, many issues regarding TR and thyroid hormone cell membrane transporters have yet to be clarified. Differences between rodent and human development are significant and need to be further explored to ensure that the relationships between thyroid hormone and human brain development are better understood.

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