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GLUCOCORTICOIDS AS A REGULATORY FACTOR FOR BRAIN TRYPTOPHAN HYDROXYLASE
Author(s) -
Sze P. Y.,
Neckers L.,
Towle A. C.
Publication year - 1976
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.1471-4159.1976.tb04453.x
Subject(s) - corticosterone , tryptophan hydroxylase , adrenalectomy , endocrinology , medicine , tryptophan , glucocorticoid , hormone , in vivo , biology , enzyme , chemistry , serotonin , amino acid , biochemistry , receptor , serotonergic , microbiology and biotechnology
—The normal developmental rise of tryptophan hydroxylase levels in neonatal rat brain was blocked by adrenalectomy. Similarly, adrenalectomy prevented the rescrpine‐induced elevation of tryptophan hydroxylase activity in brain stem of adult mice. In both cases, the effects of adrenalectomy could be reversed by replacement injections of corticosterone. Repeated injections of corticosterone (5 mg/kg daily) in fact induced a rise of brain tryptophan hydroxylase levels in neonatal brain. However, neither adrenalectomy nor repeated injections of large doses of the hormone (20 mg/kg, daily) was found to be effective in affecting the normal enzyme levels in adult brain. Apparent K m of the enzyme for substrate was unchanged by corticosterone in vivo or in vitro. These results indicate that glucocorticoids have a significant role in the regulation of brain tryptophan hydroxylase: possibly as an inducing signal during neonatal development and as a permissive factor at adult age.