Investigations on myelination in vitro: thyroid hormone receptors in cultures of cells dissociated from embryonic mouse brain.

Brain cells dissociated from 15-day-old embryonic mice and grown in culture contain both cytosolic and nuclear receptors for L-3,5,3'-triiodothyronine (L-T3). KD values for L-T3 of 3.05 X 10(-9) M and 4.2 X 10(-9) M were determined with the cytosolic and nuclear receptors respectively. These cultured cells, which are suitable for studying the regulation of myelination by T3 in vitro, display a high specificity for L-T3 in that the receptors for L-T3 do not bind D-T3, D-thyroxine, L-diiodothyronine, or DL-thyronine, and bind only small amounts of L-thyroxine.