[The metabolism of 4-14C-pregnenolone in tissue sections of human ovaries and their modification by chlormadinone acetate].

In vitro incubations with slices of two normal human ovaries and 4-14C-pregnenolone as precursor were carried out to study the possibility of a direct influence of chlormadinone acetate on the metabolism of pregnenolone. In agreement with our previous studies the incubations of the ovary from the follicle phase of the cycle yields a profile of steroids different from that of the ovary from the corpus luteum phase of the cycle. Under the experimental condition chosen, the presence of enzymes of the steroidogenic pathway responsible for the synthesis of 17alpha-hydroxy-pregnenolone, DHA, androstenediol (basic metabolites) and androstenedione represents a characteristic profile of steroids of the ovaries from the follicle phase. After the addition of chlormadinone acetate to the incubation medium, the formation of androstenedione was inhibited, whereas the basic metabolites increased. The biosynthesis of progesterone, 17alpha-hydroxyprogesterone, estrone and estradiol represents a characteristic profile of steroids of the ovaries from the corpus luteum phase. After a addition of chlormadinone acetate to the incubation medium, the formation of this characteristic profile of steroids was inhibited. The influence of chlormadinone acetate on the two different profiles of steroids indicated, that chlormadinone acetate exerts an inhibitory effect on the 3beta-hydroxysteroid-dehydrogenase-delta5-4-isome