Cellular location of cytosolic triiodothyronine binding protein in primary cultures of fetal rat brain

• Published in: Molecular and cellular endocrinology Vol. 39; no. 3; pp. 197 - 207
• Main Authors: Francon, J., Osty, J., Chantoux, F., Lennon, A.M.
• Format: Journal Article
• Language: English
• Published: Shannon Elsevier Ireland Ltd 01.03.1985; Elsevier
• Subjects: Animals; Biochemistry and metabolism; Biological and medical sciences; Brain - embryology; Brain Chemistry; Cells, Cultured; Central nervous system; Cytosol - analysis; DNA - analysis; Electrophoresis, Polyacrylamide Gel; Female; Fundamental and applied biological sciences. Psychology; neuron and glial cell culture; Pregnancy; Rats; Receptors, Cell Surface - analysis; Receptors, Thyroid Hormone; thyroid hormone receptors; Vertebrates: nervous system and sense organs; neuron and glial cell culture; thyroid hormone receptors; Cell culture; Glial cell; Rat; Rodentia; Aminoacid derivative hormone; Brain (Vertebrata); Cytosol; Binding protein; Vertebrata; Mammalia; Neuron; Fetus; Thyroid hormone
• ISSN: 0303-7207; 1872-8057
• DOI: 10.1016/0303-7207(85)90063-2

The evolution of a cytosolic triiodothyronine (T 3) binding protein was studied in primary cultures of fetal rat brain. These cultures exhibited neuronal characteristics during the first week. T 3 binding activity in cell supernatants increased during this period from 39 ± 7 (mean ± SD) to 159 ± 24 fmoles T 3/culture flask. A similar increase was observed in the soluble proteins. After day 8, neuronal death occurred and glial cells multiplied and differentiated. On day 11 an 86% drop in the binding activity was observed (24 ± 7 fmoles T 3/culture flask); the pool of soluble proteins remained stable. Scatchard analysis revealed two types of binding site in both 7- and 14-day cultured cell cytosols. Binding affinities were similar in both cytosols ( K M − 1.5 × 10 9 M −1 K A2 ~ 1 × 10 8 M −1); in contrast, the number of sites was 4-fold smaller in 14-day cytosols. In subcultures mostly composed of glial cells, almost the same affinities were measured, but the numbers of both types of sites were 20 times smaller than in 7-day cells. These results show that in cell cultures from embryonic rat telencephalon, cytosolic T 3 binding protein is mainly located in the neurons.