Effects of the anti-androgen TSAA-291 on the gonadotrophin secretion were studied.
(1) A single subcutaneous or oral administration of TSAA-291 and its caproate induced the ovulation in the proestrous rat of which the spontaneous ovulation was blocked by the treatment with chlorpromazine. (2) A single subcutaneous administration of TSAA-291 at 2.4 mg/kg to the adult male rat induced only a slight elevation in the serum LH and FSH levels at 30 min after the administration. Successive intramuscular administrations of TSAA-291 to the adult male rat for 2 or 4 weeks resulted in significant decreases in the serum LH and FSH levels at high dose levels. A dose-dependent decrease in the serum LH level but not FSH level was observed in the orchiectomized rat. (3) Successive intramuscular adminstrations of TSAA-291 at high dose levels to the male rat suppressed the plasma testosterone level in the testicular venous blood and general circulation.