Effect of in vivo administration of 5 alpha reductase inhibitors on epididymal function

Progesterone, epitestosterone (4-androstene-17 alpha-ol-3-one, EpiT) and 4- androstene-3-one-17 beta-carboxylic acid (COOH), three known in vitro inhibitors of 5 alpha reductase, were injected daily for 30 days to male rats to study their effect on some parameters of epididymal function. Progesterone at the dose of 750 and 2000 micrograms/day decreased fertility by 59% and 50% respectively. EpiT at a dose of 1500 micrograms/day decreased fertility by 74%. These treatments did not change the sperm counts in the cauda epididymis. Treatment with COOH did not decrease fertility. Progesterone at 750 and 2000 micrograms/day and EpiT at 750 micrograms/day decreased the weight of the epididymis, prostate and seminal vesicles. None of the compounds tested produced variations in body weight or in the weight of liver and testis. The 5 alpha reductase activity of epididymis, testis and liver was diminished by progesterone treatment, while EpiT decreased only that of testis and liver.