Inhibition of steroid-mediated induction of delta-aminolevulinic acid synthase by 2-diethylaminoethyl-2,2-diphenylvalerate HCl (SKF 525-A).
The inhibition of the steroid-mediated induction of delta-aminolevulinate synthase, the rate-limiting enzyme in hepatic porphyrin-heme biosynthesis, by 2-diethylaminoethyl-2,2-diphenylvalerate HCl (SKF 525-A) as studied in cultured chick embryo liver cells. The formation of porphyrins in response to cyproterone, a synthetic steroid, was inhibited in a time-dependent manner by SKF 525-A, an inhibitor of several drug metabolizing enzyme systems. This action is a result of an inhibitory effect of SKF 525-A on the cyproterone-mediated induction of delta-aminolevulinate synthase; SKF 525-A also inhibited the induction of the enzyme by the naturally occurring 5 beta-H steroids, etiocholanolone and pregnanolone. Employing [3H]etiocholanolone, we provide evidence that this inhibition is not associated with either decreased uptake or an altered metabolism of the steroid. Moreover, approx 4-6-fold more radioactivity was associated with [3H]etiocholanolone-treated cells cultured in the presence of SKF 525-A. Alternative mechanisms for the induction of delta-aminolevulinate synthase by steroids are proposed which do not require the interaction of steroid-receptor complex with the genome.
D000624:5-Aminolevulinate Synthetase / Q000096:biosynthesis*; D000818:Animals; D002642:Chick Embryo; D003534:Cyproterone / Q000494:pharmacology; D004790:Enzyme Induction; D005043:Etiocholanolone / Q000494:pharmacology; D008099:Liver / Q000187:drug effects / Q000201:enzymology*; D011280:Pregnanolone / Q000494:pharmacology; D011335:Proadifen / Q000494:pharmacology*; D019946:Propylene Glycol; D011409:Propylene Glycols / Q000494:pharmacology; D013256:Steroids / Q000494:pharmacology*; D013997:Time Factors
D011409:Propylene Glycols; D013256:Steroids; D019946:Propylene Glycol; D005043:Etiocholanolone; D011335:Proadifen; D011280:Pregnanolone; D003534:Cyproterone; D000624:5-Aminolevulinate Synthetase