Investigations on myelination in vitro: regulation of 2,3'-cyclic nucleotide 3'-phosphohydrolase by thyroid hormone in cultures of dissociated brain cells from embryonic mice.
The direct influence of L-3,3',5-triiodothyronine (T3) on the development of 2',3'-cyclic nucleotide 3'-phosphohydrolase (EC 3.1.4.37, CNPase) is demonstrated by using an in vitro culture system of dissociated embryonic mouse brain cells. Serum from a thyroidectomized calf, which contained low levels of T3 (31 ng/100 ml), and thyroxine, T4 (less than 1 micrograms/ml), was used in the culture medium in place of normal calf serum (T3, 103 ng/100 ml; T4, 5.7 micrograms/ml) to render the culture responsive to exogenously added T3. The lower levels of enzyme activity observed in the presence of such a deficient medium could be restored to normal values by T3 supplementation. Half-maximal effect was obtained with 2.5 X 10(-9) M-T3. Three days of hormone treatment resulted in the maximal stimulation of CNPase. T4 was less effective in inducing CNPase activity and the inactive analog of the hormone, reverse T3 (3,3',5'-T3) was ineffective. The morphological appearance of the cells was characterized by deformed (smaller size and less in number) reaggregates in the cultures, lacking hormone.
D015087:2',3'-Cyclic-Nucleotide Phosphodiesterases / Q000378:metabolism*; D000818:Animals; D001921:Brain / Q000187:drug effects / Q000201:enzymology*; D002478:Cells, Cultured; D003470:Culture Media; D004622:Embryo, Mammalian; D004790:Enzyme Induction; D007037:Hypothyroidism / Q000503:physiopathology; D007700:Kinetics; D051379:Mice; D010727:Phosphoric Diester Hydrolases / Q000378:metabolism*; D014284:Triiodothyronine / Q000494:pharmacology*
D003470:Culture Media; D014284:Triiodothyronine; D015087:2',3'-Cyclic-Nucleotide Phosphodiesterases; D010727:Phosphoric Diester Hydrolases