title: Investigations on myelinogenesis in vitro: regulation of 5'-nucleotidase activity by thyroid hormone in cultures of dissociated cells from embryonic mouse brain.
abstract: The developmental pattern of the myelin-associated 5'-nucleotidase and its regulation by L-3,3',5,-triiodothyronine (T3) have been demonstrated in a culture system of cells dissociated from embryonic mouse brain. Hypothyroid calf serum containing low levels of T3 (31 ng/100 ml), and thyroxine, T4 (less than 1 microgram/ml), was used in the culture medium in place of normal calf serum (T3, 103 ng/100ml; T4, 5.7 micrograms/ml) to render the cultures responsive to exogenously added T3. By means of T3 supplementation, the lower levels of enzyme activity observed in the cultures grown in the presence of hypothyroid calf-serum containing medium could be restored to a considerable extent although not completely to normal values. Half-maximal stimulatory effect was obtained at 3.9 X 10(-8)M T3 concentration. Among the various substrates tested, 5'-AMP, 5'-UMP and 5'-CMP were equally good, while 5'-GMP yielded approximately half the activity.
mesh_terms: D015720:5'-Nucleotidase; D000818:Animals; D001921:Brain / Q000201:enzymology*; D004790:Enzyme Induction; D005260:Female; D008274:Magnesium / Q000378:metabolism; D051379:Mice; D009186:Myelin Sheath / Q000201:enzymology*; D009708:Nucleotidases / Q000378:metabolism*; D009836:Oligodendroglia / Q000201:enzymology; D011247:Pregnancy; D013379:Substrate Specificity; D013963:Thyroid Hormones / Q000502:physiology*
chemical_list: D013963:Thyroid Hormones; D009708:Nucleotidases; D015720:5'-Nucleotidase; D008274:Magnesium