The inhibition of the conversion of testosterone into 5alpha-dihydrotestosterone in the reproductive organs of the male rat.

The inhibition of testosterone 5alpha-reductase activity by 3-oxo-4-androstene-17beta-carboxylic acid in the male reproductive organs of the rat was demonstrated in vitro. The medium for incubation of caput epididymis showed the highest concentration of 5alpha-dihydrotestosterone (5alpha-DHT) whereas the highest concentration of testosterone (T) was recorded in medium for incubation of decapsulated testis after two hours of incubation. The 3-oxo-4-androstene-17beta-carboxylic acid (1.58 X 10(-5)M) inhibited the conversion of T to 5alpha-DHT in all the organs tested (testis, caput and cauda epididymis and ventral prostate) under identical incubation conditions.