19-hydroxy-4-androstene-3-17-dione and 19-norandrostenedione

The conversion of androgen to estrogen is mediated by aromatase activity, and 19-hydroxylase and C10-19lyase are seen to be involved in C19-demethylation. The present study is to demonstrate C10-19lyase activity in adrenal tissue. Fetal bovine and pig adrenal tissue homogenates were incubated with 14C-androstenedione(A) and NADPH under air. The products 14C-19-OHA, 14C-19-norA, with added carrier standard 3H-19-OHA, 3H-19-norA were separated and purified by T.L.C.. The identification of 19-norA was established by recrystallization and that of 19-OHA by C.C.D.. The 3H/14C ratios of the products 19-norA were found to be constant in repeated crystallization. The amount of 19-OHA from A in fetal adrenal tissue was 30.0nmol/h/g protein, and that of 19-norA from A was 12.59pmol/h/g protein. C10-19lyase activity from 19-OHA, calculated by the amounts of 19-norA in fetal, bovine and pig adrenal tissue, was 49.7, 3.50, 10.3pmol/h/g protein, respectively. This is the first report to demonstrate androgen C10-19lyase in human fetal adrenal tissue, and it is assumed that fetal adrenal tissue forms 19-norA via 19-OHA.

Topics: Adrenal Glands; Androgens; Androstenedione; Animals; Cattle; Culture Techniques; Fetus; Humans; Lyases; Swine

The origin and biosynthesis of 4-oestrene-3,17-dione (19-norandrostenedione), a major steroid in porcine ovarian follicular fluid, was investigated by culturing granulosa cells from 4-6 mm follicles of prepubertal gilts with radiolabelled androstenedione and 19-hydroxyandrostenedione. Steroid metabolites were purified by solvent extraction and lipophilic column chromatography, and analysed by C18 reverse-phase high-performance liquid chromatography. 19-Hydroxyandrostenedione, 19-norandrostenedione and oestradiol-17 beta were obtained as major metabolites from androstenedione, while 19-norandrostenedione and oestradiol-17 beta were the major products from 19-hydroxyandrostenedione. Serum alone or serum plus FSH significantly enhanced formation of 19-norandrostenedione and oestradiol-17 beta from each substrate, compared with controls. Micromolar concentrations (1 mumol/l) of 4-hydroxyandrostenedione, an aromatase inhibitor, significantly reduced formation of 19-norandrostenedione and oestradiol-17 beta by granulosa cells cultured with serum and FSH. Formation of 19-norandrostenedione and oestradiol-17 beta from androstenedione and 19-hydroxyandrostenedione was also significantly inhibited by aminoglutethimide phosphate, a cytochrome P-450 inhibitor known to block the conversion of androstenedione to oestrogens. Ketoconazole, an inhibitor of the cytochrome P-450 dependent 17,20-lysase, blocked formation of 19-norandrostenedione and oestradiol-17 beta only at millimolar concentrations. These results suggest that 19-norsteroid and oestrogen formation from C19 aromatizable androgens may share a common or overlapping pathway, and imply that 19-norsteroid and oestrogen synthesis is mediated by cytochrome P-450 dependent enzymes.

Topics: Aminoglutethimide; Androstenedione; Animals; Cells, Cultured; Female; Granulosa Cells; Ketoconazole; Swine

19-Oxoandrostenedione, the product of 19-hydroxyandrostenedione by the 19-oxidase activity of the purified P-450(11)beta system of adrenal cortex mitochondria, was further oxidized and demethylated at the 10-position to give the C18-steroids, estrone (aromatase reaction) and 19-norandrostenedione (nonaromatizing 10-demethylase or C10-19 lyase reaction). These reactions, together with the initial hydroxylation of androstenedione at C19, form a sequence of P-450(11)beta-catalyzed C19-steroid 19-monooxygenase reactions. P-450(11)beta is thus similar to placental endoplasmic P-450AROM in some of its substrate specificity, but the two forms of P-450 appear to be different in both physiology and properties.

Topics: Adrenal Cortex; Androstenedione; Animals; Aromatase; Cattle; Chromatography, High Pressure Liquid; Estrone; Gas Chromatography-Mass Spectrometry; Hydroxylation; Kinetics; Mitochondria; Oxidoreductases; Steroid 11-beta-Hydroxylase; Steroid Hydroxylases

Digoxin-like immunoreactivity of 19-OH-androst-4-ene-3,17-dione and 19-NOR-androst-4-ene-3,17-dione estimated by radioimmunoassay was by about four orders of magnitude lower than that of digoxin.

Topics: Androstenedione; Antibodies; Antigen-Antibody Complex; Cross Reactions; Digoxin; Immunoenzyme Techniques; Iodine Radioisotopes