Thyroxine transport in choroid plexus

Journal Article · Thu Oct 15 04:00:00 EDT 1987 · J. Biol. Chem.; (United States)

OSTI ID:5727861

Dickson, P W; Aldred, A R; Menting, J G; Marley, P D; Sawyer, W H; Schreiber, G

The role of the choroid plexus in thyroid hormone transport between body and brain, suggested by strong synthesis and secretion of transthyretin in this tissue, was investigated in in vitro and in vivo systems. Rat choroid plexus pieces incubated in vitro were found to accumulate thyroid hormones from surrounding medium in a non-saturable process. At equilibrium, the ratio of thyroid hormone concentration in choroid plexus pieces to that in medium decreased upon increasing the concentration of transthyretin in the medium. Fluorescence quenching of fluorophores located at different depths in liposome membranes showed maximal hormone accumulation in the middle of the phospholipid bilayer. Partition coefficients of thyroxine and triiodothyronine between lipid and aqueous phase were about 20,000. After intravenous injection of /sup 125/I-labeled thyroid hormones, choroid plexus and parts of the brain steadily accumulated /sup 125/I-thyroxine, but not (/sup 125/I)triiodothyronine, for many hours. The accumulation of /sup 125/I-thyroxine in choroid plexus preceded that in brain. The amount of /sup 125/I-thyroxine in non-brain tissues and the (/sup 125/I)triiodothyronine content of all tissues decreased steadily beginning immediately after injection. A model is proposed for thyroxine transport from the bloodstream into cerebrospinal fluid based on partitioning of thyroxine between choroid plexus and surrounding fluids and binding of thyroxine to transthyretin newly synthesized and secreted by choroid plexus.

• Research Organization: Univ. of Melbourne, Parkville, Victoria, Australia
• OSTI ID: 5727861
• Journal Information: J. Biol. Chem.; (United States), Journal Name: J. Biol. Chem.; (United States) Vol. 262:29; ISSN JBCHA
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
AMINO ACIDS
ANIMALS
BETA DECAY RADIOISOTOPES
BIOCHEMICAL REACTION KINETICS
BIOLOGICAL MODELS
BODY
BRAIN
CARBOXYLIC ACIDS
CELL CONSTITUENTS
CELL MEMBRANES
CENTRAL NERVOUS SYSTEM
DAYS LIVING RADIOISOTOPES
ELECTRON CAPTURE RADIOISOTOPES
ESTERS
FLUORESCENCE
HORMONES
IN VITRO
IN VIVO
INTERMEDIATE MASS NUCLEI
IODINE 125
IODINE ISOTOPES
ISOTOPE APPLICATIONS
ISOTOPES
KINETICS
LIPIDS
LIPOSOMES
LUMINESCENCE
MAMMALS
MEMBRANE TRANSPORT
MEMBRANES
NERVOUS SYSTEM
NUCLEI
ODD-EVEN NUCLEI
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
ORGANIC IODINE COMPOUNDS
ORGANIC PHOSPHORUS COMPOUNDS
ORGANOIDS
ORGANS
PEPTIDE HORMONES
PHOSPHOLIPIDS
RADIOISOTOPES
RATS
REACTION KINETICS
RODENTS
THYROID HORMONES
THYROXINE
TRACER TECHNIQUES
TRIIODOTHYRONINE
VERTEBRATES