Effect of experimental bilateral cryptorchidism on in vitro metabolism of progesterone by rat testis.

Changes in the in vitro capacity to convert progesterone (4-pregnen-3,20-dione) to its metabolites were studied in testes of experimentally cryptorchid adult rats for varying lengths of time. Cryptorchidism resulted in a decrease in testicular, seminal vesicle, and prostatic weights, implying suppression of in vivo androgen production and this decrease was confirmed in vitro. Cryptorchidism decreased the conversion of androgen from progesterone and increased the formation of 20 alpha-dihydroprogesterone (20 alpha-dihydroxy-4-pregnen-3-one). This indicated that enzyme activity for androgen analysis synthesis from a progesterone substrate in the rat testis was heat-sensitive and suggested 20 alpha-dihydroprogesterone may have an important role as the primary steroid produced in experimental cryptorchidism.