Thyroid hormone exerts its actions by binding to nuclear receptors and
regulating gene expression. Gene expression regulation by thyroid hormone in the
brain is highly complex, with thousands of genes under the direct or indirect influence
of T3. Adding to the complexity, gene dependence of T3 is age- and region-dependent,
with diverse time window sensitivity. The maximal gene expression responses to T3 in
rodents extend from the last 2-3 days of fetal life to the end of the first month, peaking
around postnatal days 15-21. T3 regulates genes involved in almost all aspects of brain
function, from developmental genes to genes involved in metabolic and cell signaling
pathways. In most cases, the effect of T3 is to fine-tune the relative abundance of
selected gene products at the right time and place, promoting maturational processes
during developmental transitions.
Keywords: Astrocytes, Cerebrocortical cells, Cell migration, Development, Extracellular matrix, Neurotransmitter receptors, Potassium channels, Retinoic acid, Transcriptional regulation.
