DIFFERENTIAL-EFFECTS OF ADRENOCORTICOTROPIC HORMONE ON ADRENAL MICROSOMAL XENOBIOTIC AND STEROID-METABOLISM IN GUINEA-PIGS

  • 1 January 1982
    • journal article
    • research article
    • Vol. 10  (4) , 326-329
Abstract
The effects of ACTH administration to guinea pigs on the activities of adrenal microsomal monooxygenases were studied. ACTH treatment decreased the rates of adrenal benzphetamine (BZ) demethylation and benzo[a]pyrene (BP) hydroxylation but had no effect on the same reactions in hepatic microsomes. Adrenal microsomal steroid hydroxylation reactions were unaffected (21-hydroxylation) or stimulated (17.alpha.-hydroxylation) by ACTH. Although ACTH treatment decreased adrenal BP hydroxylase activity, relative quantity of the various BP metabolites, as determined by high performance liquid chromatography, did not change. Adrenal microsomal cytochrome P-450 concentrations were decreased by ACTH but proportionately less than the decreases in adrenal xenobiotic metabolism. The maximal type I spectral changes produced by xenobiotics in adrenal microsomes were decreased in size by ACTN treatment, but steroid-induced difference spectra were unaffected. ACTH selectively decreases the rates of adrenal xenobiotic metabolism, perhaps by producing a selective decline in the concentration(s) of those cytochromes P-450 involved in the metabolism of foreign compounds.

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