Studies of 11beta-hydroxylation by beef adrenal mitochondria

In vitro bioconversion of [14C]androstenedione by testes of the Siamese fighting fish Betta splendens Regan (Anabantoidei, Belontiidae)

Minced testes of the Siamese fighting fish Betta splendens were incubated with [14C]androstenedione at 27 degrees C for 15, 30, 60, and 120 min. The metabolic products were characterized by paper and thin-layer chromatography, derivative formation, and eventually by crystallization to constant specific activity. After 2 hr of incubation 80.5% of total radioactivity was converted to 11-oxygenated androgens. 11-Ketotestosterone was the main metabolite (56.2%). Our data suggest the existence of two biosynthetic pathways for the formation of 11-ketotestosterone from androstenedione. The sequence androstenedione----testosterone----11 beta-hydroxytestosterone----11-ketotestosterone predominates. To a lesser extent 11 beta-hydroxylation takes place as the first step--followed by formation of 11 beta-hydroxytestosterone and its subsequent oxidation to 11-ketotestosterone.

Androstenedione-mediated inhibition of 11 beta-hydroxylation in monolayer cell cultures of fetal calf adrenals

The possibility that the formation of androstenedione by fetal calf adrenal cells in culture is linked to their decreased ability to form cortisol and corticosterone was investigated. Fetal calf adrenal cells metabolise radioactive adrostenedione to two major products which coelute on thin layer chromatography with 11 beta-hydroxyandrostenedione and 11 beta-hydroxytestosterone. When the cells are incubated with 11-deoxycortisol or 11-deoxycorticosterone in the presence of androstenedione there is a dose dependant inhibition of cortisol and corticosterone formation. Further studies with progesterone showed an accumulation of 11-deoxycortisol and 11-deoxycorticosterone in cells incubated simultaneously with androstenedione. The results demonstrate that exogenous androstenedione can have dramatic effects on steroidogenesis in the fetal calf adrenal and suggest that the accumulation of androstenedione in the medium of cultured andrenocortical cells is responsible, at least in part, for the decreased formation of cortisol and corticosterone.

Kinetics of plasma corticosteroids during metyrapone infusion in man

The effect of metyrapone on plasma kinetics of cortisol (F), 11-deoxycortisol (S), corticosterone (B), 11-deoxycorticosterone (DOC), aldosterone (Aldo) and 17 hydroxyprogesterone (17 OHP) was studied in ten normal prepubertal children intravenously infused with the drug (1 gm/1.73 m2 body surface area in 4 h). Similar falls in F, B and Aldo were observed during the first hour expressing similar sensitivity of the 11 hydroxylases to the drug. The effect of the compensatory increase of endogenous ACTH could be detected after 1 hour by the rise in 17 OHP. However the concentrations of the 11-hydroxy compounds, F, B and Aldo, remained low throughout the infusion period. From the second hour onwards, facilitation of the synthesis of DOC was noticed. After the end of infusion, the levels of the precursors decreased and F and B were restored to initial values. Aldo remained low probably due to the inhibitory effect of the elevated DOC on the renin-angiotensin system.