Endocrine Abstracts

Thyroid hormone plays an important role in the development of tissues, in particular the brain, and in the regulation of their metabolic activity throughout life. Most of the actions of thyroid hormone are initiated by binding of T3 to its nuclear receptor, resulting in an altered transcription of thyroid hormone-responsive genes. Also the metabolism of thyroid hormone by the deiodinases D1, D2 and D3 takes place intracellularly. D2 and D3 are important for local regulation of...

Thyroid hormone 3,5,3′-triiodothyronine (T3) and its precursor thyroxine (T4) are iodinated compounds known to influence gene expression in virtually every vertebrate tissue. Fundamentally, thyroid hormone signaling results from the interaction of nuclear thyroid hormone receptors (TRs) with specific target gene promoters, a process that can either enhance or repress transcription. This process is modulated via binding of thyroid hormone, the ligand...

Hypothyroidism delays bone development, whilst thyrotoxicosis causes osteoporosis. Recent studies have challenged understanding of skeletal responses to thyroid hormone by proposing TSH as a negative regulator of bone turnover and suggesting bone loss in hyperthyroidism results from TSH deficiency and not T3-excess. To investigate, we characterised mice with mutations or deletions of the genes encoding T3 receptor (TR) α and TRβ. Endochondral ossification was retarde...

Thyroxine is crucial for normal human brain development in utero and for the first two years after birth. Brain damage through deficiency of T4 is irreversible and the degree and spectrum of subsequent neurodevelopmental disorders is dependent on the timing and severity of T4 deprivation; this presentation will review the current clinical evidence.Maternal to fetal transfer of thyroxine is essential for the first half of gestation, and to a lesser, and d...