WIRKUNG VON 1,2α-METHYLEN-6-CHLOR-Δ4,6-PREGNADIEN-17α-OL-3,20-DION (CYPROTERON) AUF DIE BIOGENESE VON C19-STEROIDEN IN RATTENTESTES

Abstract

ABSTRACT The effect of 1,2α-methylene-6-chloro-pregna-4,6-dien-17α-ol-3,20-dione (Cyproterone) on the formation of C19-steroids from 17α-hydroxyprogesterone was studied in the 20 000 × g supernatants and the microsomal fractions obtained from the testis of young (5 weeks ± 5 days) and old (5 months ± 14 days) rats. Under the experimental conditions chosen, cyproterone (final concentration 2.7-27 μmoles/1) inhibited the biogenesis of C19-steroids to an extent of 20–80%. On the basis of enzyme-kinetic studies, cyproterone belongs to the class of »mixed type inhibitors«. The investigation of the pattern of the C19-steroid metabolites showed that, after the addition of cyproterone, the formation of testosterone, androst-4-ene-3,17-dione and the »polar« fraction was inhibited, whereas the androsterone fraction mostly increased. These results suggest that cyproterone affects not only the activity of the desmolase, but also the activities of the enzymes involved in the metabolism of C19-steroids. The experiments reported are, to a large extent, in agreement to the already known fact that the activity of the desmolase depends upon the age of rats. However, the biogenesis of C19-steroids from C21-steroids is greatly influenced by the preparation of the relevant enzyme systems and by the experimental conditions.