Studies of corticosterone binding and metabolism in rat thymocytes

• Published in: Biochimica et biophysica acta Vol. 264; no. 3; pp. 557 - 565
• Main Authors: Augustyn, Joan M., Brunkhorst, Willa K.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 16.05.1972
• Subjects: Acetates; Acylation; Adrenal Glands - physiology; Adrenalectomy; Animals; Biotransformation; Cell Fractionation; Cell Nucleus - metabolism; Cells - cytology; Cells - metabolism; Chromatin - metabolism; Chromatography, Thin Layer; Corticosterone - metabolism; Cytoplasm - metabolism; Hydroxysteroids - biosynthesis; Ketosteroids - biosynthesis; Kinetics; Male; Pregnanes - biosynthesis; Pregnanes - metabolism; Rats; Receptors, Drug; Thymus Gland - cytology; Thymus Gland - metabolism; Tritium
• ISSN: 0304-4165; 0006-3002; 1872-8006
• DOI: 10.1016/0304-4165(72)90019-0

1. 1. In vivo and in vitro experiments established that the radioactive compound bound to chromatin was corticosterone, thus supporting the hypothesis that the “specific” receptor for glucocorticoids in thymocytes is a component(s) of chromatin. 2. 2. Identification of metabolites of corticosterone present in the cytoplasmic fraction, in in vitro experiments, showed that only the product of oxidation at C-11, Δ 4-pregnene-21-ol-3,11,20-trione, occurs to any significant extent. 3. 3. In in vivo experiments, significant amounts of the total radioactivity present in cytoplasm and nuclei occur as the following metabolites of corticosterone: Δ 4-pregnene-21-ol-3,11,20-trione, Δ 4-pregnene-11 β,20–21-triol-3-one, 5 β-pregnane-3 α,11 β,20 β,21-tetro, and 5β-pregnane-3α,11-β,21-triol-20-one. It is suggested that the latter three metabolites do not originate in the thymus but reach it via the circulation. 4. 4. Incubation of rat thymocytes in Eagle's minimal essential medium containing concentrations of corticosterone from 1 nM to 3 μM suggested the presence of “specific” binding site for corticosterone, in both cytoplasm and nucleus, which were saturated at about 100 nM.