Reversible inhibitory effect of the non-steroidal antiandrogen flutamide (SCH 13521) on spermatogenesis in mice.

The effects of a prolonged subcutaneous administration of SCH 13521 dissolved in 0.3% hydroxypropyl cellulose (2-8 weeks in daily doses of 0.2 or 1.0 mg amounting to an estimated equivalent of experimental and curative doses used by others in laboratory animals and men) were studied in males of the mouse inbred strain C57BL/6. Following the treatment, the activity of spermatogenesis (expressed as the mean number of seminiferous tubules containing mature sperm and epididymal sperm count) was inhibited while the testis weight was not reduced, obviously due to an absolute increase of the interstitial tissue which was a marked histological feature of the testes, particularly following the higher doses of SCH 13521. Lower doses and shorter-lasting administration of the compound seem to inhibit the activity more effectively because after a prolonged administration reparatory processes tend to be triggered via a stimulatory effect on the synthesis of testosterone in Leydig cells. The solvent alone, hydroxypropyl cellulose, had some inhibitory effect on spermatogenesis. The lymphoid system remained both morphologically and functionally unaffected by SCH 13521 unlike the steroidal antiandrogen cyproterone actetate.