title: Dynamic mRNA distribution pattern of thyroid hormone transporters and deiodinases during early embryonic chicken brain development.
abstract: Maternal thyroid hormones (THs) are important in early brain development long before the onset of embryonic TH secretion, but information about the regulation of TH availability in the brain at these early stages is still limited. We therefore investigated in detail the mRNA distribution pattern of the TH activating type 2 and inactivating type 3 deiodinases (D2 and D3) and the TH transporters, organic anion transporting polypeptide 1c1 (Oatp1c1) and monocarboxylate transporter 8 (Mct8), in chicken embryonic brain as well as in retina and inner ear from day 3 to day 10 of development. Oatp1c1, Mct8 and D3 are expressed in the choroid plexus and its precursors allowing selective uptake of THs at the blood-cerebrospinal fluid-barrier with subsequent inactivation of excess hormone. In contrast, the developing blood-brain-barrier does not express Oatp1c1 or Mct8 but appears to be a site for TH activation by D2. Expression of D3 in several sensory brain centers may serve as protection against premature TH action. Expression of D2 and Mct8 but not D3 in the developing pituitary gland allows accumulation of active THs even at early stages. Mct8 is widely expressed in gray matter throughout the brain. This is the first comprehensive study on the dynamic distribution pattern of TH-transporters and deiodinases at stages of embryonic brain development when only maternal THs are available. It provides the essential background for further research aimed at understanding early developmental processes depending on maternal THs.
authors: Laboratory of Comparative Endocrinology, Animal Physiology and Neurobiology Section, Department of Biology, KU Leuven, B-3000 Leuven, Belgium.
authors: S
authors: S
authors: Geysens
authors: J L
authors: JL
authors: Ferran
authors: S L J
authors: SL
authors: Van Herck
authors: P
authors: P
authors: Tylzanowski
authors: L
authors: L
authors: Puelles
authors: V M
authors: VM
authors: Darras
mesh_terms: D000818:Animals; D001692:Biological Transport / Q000235:genetics*; D001921:Brain / Q000196:embryology* / Q000378:metabolism; D002642:Chick Embryo; D047108:Embryonic Development / Q000502:physiology*; D018507:Gene Expression Regulation, Developmental; D007453:Iodide Peroxidase / Q000145:classification / Q000235:genetics* / Q000378:metabolism; D027501:Monocarboxylic Acid Transporters / Q000235:genetics / Q000378:metabolism; D027361:Organic Anion Transporters / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism*; D013963:Thyroid Hormones / Q000378:metabolism*
chemical_list: D027501:Monocarboxylic Acid Transporters; D027361:Organic Anion Transporters; D012333:RNA, Messenger; D013963:Thyroid Hormones; D007453:Iodide Peroxidase