Influence of an aromatase inhibitor (4-acetoxy-4-androstene-3,17-dione) on experimentally induced impairment of spermatogenesis in immature rats.

Subcutaneous treatment of immature male rats with an estrogen precursor, 19-hydroxy-testosterone (19-OHT), at a daily dose of 1 mg/animal for 14 days leads to a significant decrease in the weight of testis, ventral prostate and seminal vesicle. The peripheral levels of LH are lowered. Testicular histology indicates that the effects of 19-OHT are very similar to the known of effect induced by estradiol-17 beta. 19OHT induces a marked impairment of spermato- and spermiogenesis. The maturation division is completely inhibited. The effect of 19-OHT on spermatogenesis is partially reversed by concomitant administration of an aromatase inhibitor (4-acetoxy-4-androstene-3.17-dione, (4-AA] at a dose of 1 mg/animal/day s.c. Meiotic activity is restored, and the weights of genital organs and the serum LH values increase. 4-AA alone has no appreciable effect on the parameters examined in this study. The present results suggest that specific inhibitors of estrogen biosynthesis might not only be useful to investigate the patho-physiological role of estrogens on spermatogenesis, but also be suitable to some extent for the treatment of estrogen-induced infertility in men suffering from idiopathic oligozoospermia.