Depletion of [3H]Methyltrienolone Cytosol Binding in Glucocorticoid-Induced Muscle Atrophy (42001)

T. T. Kurowski, J. A. Capaccio, Robert Treat Chatterton Jr, R. C. Hickson

Research output: Contribution to journalArticle

3 Scopus citations

Abstract

The present study was undertaken to determine cytosol binding properties of [3H]methyltrienolone, a synthetic androgen, in comparison with [3H]dexamethasone, a synthetic glucocorticoid, under conditions of glucocorticoid excess in skeletal muscle. Male hypophysectomized rats received either seven daily subcutaneous injections of cortisone acetate (CA) (100 mg·kg- body wt) or the vehicle, 1% carboxymethyl cellulose. Following treatment, both [3H]dexamethasone and [3H]methyltrienolone-receptor concentrations were decreased from those in vehicle-treated rats by more than 90 and 80%, respectively, in CA-treated animals. Scatchard analysis of [3H]methyltrienolone binding in muscles of vehicle-treated animals became nonlinear at high concentrations of labeled ligand and were reanalyzed by a two-component binding model. The lower affinity, higher capacity component, which was attributed to binding of methyltrienolone to a “dexamethasone” component, disappeared in muscles of CA-treated rats and Scatchard plots were linear. Receptor concentrations of the higher affinity lower capacity “methyltrienolone” component were similar in muscles of vehicle-treated and CA-treated groups. From competition studies, the high relative specificities of glucocorticoids for [3H] methyltrienolone binding in muscles of vehicle-treated animals were markedly reduced by CA treatment. In addition, the binding specificity data also showed strong competition by progesterone and methyltrienolone for [3H]dexamethasone binding and estradiol-17β for [3H]methyltrienolone binding. These results demonstrate that most of the [3H]methyltrienolone binding is eliminated under in vivo conditions of glucocorticoid excess. Furthermore, the competitiveness of various steroids for receptor binding suggests that rat muscle may not contain classic (ligand-specific) glucocorticoid and androgen receptors.

Original languageEnglish (US)
Pages (from-to)215-221
Number of pages7
JournalProceedings of the Society for Experimental Biology and Medicine
Volume178
Issue number2
DOIs
StatePublished - Jan 1 1985

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)

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