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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
Author(s) -
Bhat Narayan R.,
Shanker Gouri,
Pieringer Ronald A.
Publication year - 1982
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1982.tb12543.x
Subject(s) - triiodothyronine , medicine , endocrinology , in vitro , hormone , nucleotide , stimulation , thyroid , embryo , biology , microgram , cyclic nucleotide , enzyme , embryonic stem cell , reverse triiodothyronine , biochemistry , microbiology and biotechnology , gene
The direct influence of l ‐3,3′,5‐triiodothyronine (T 3 ) 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 T 3 (31 ng/100 ml), and thyroxine, T 4 (<1 μg/ml), was used in the culture medium in place of normal calf serum (T 3 , 103 ng/100 ml; T 4 , 5.7 μg/ml) to render the culture responsive to exogenously added T 3 . The lower levels of enzyme activity observed in the presence of such a deficient medium could be restored to normal values by T 3 supplementation. Half‐maximal effect was obtained with 2.5 ± 10 −9 m ‐T 3 . Three days of hormone treatment resulted in the maximal stimulation of CNPase. T 4 was less effective in inducing CNPase activity and the inactive analog of the hormone, reverse T 3 (3,3′,5′‐T 3 ) was ineffective. The morphological appearance of the cells was characterized by deformed (smaller size and less in number) reaggregates in the cultures, lacking hormone.