Thyroid Hormone and the White Matter of the Central Nervous System: From Development to Repair

The role of thyroid hormone (TH) on brain development, and particularly in myelination, is well known since many decades, as testified by the severe structural and functional consequences of congenital hypothyroidism. This role during development, the consideration that the early TH supplementation restores myelination capability, and the fact the cell responsible for developmental myelination and remyelination is the same, i.e., the oligodendrocyte precursor cell (OPC), claimed the attempt to improve myelin repair in the adulthood via TH supplementation. In this chapter, the impact of TH on development, homeostasis, and repair of the myelin in the CNS will be reviewed, focusing on the regulation of the TH tissue signaling during physiological and pathological conditions affecting myelination and/or myelin repair during early postnatal age and during the adulthood. The impact of the tissue inflammation on molecular mediators of the TH cellular action and metabolism will be discussed, with regard to the consequences on the biology of the OPC.