Inhibition of the postcastration rise of luteinizing hormone and follicle-stimulating hormone in female rhesus monkeys (Macaca mulatta) by the administration of a luteinizing hormone-releasing hormone inhibitory analog ([N-Ac-D-Trp1-3,D-p-Cl-phe2,D-Phe6,D-Ala10]-LH-RH).

Regularly cycling rhesus monkeys were bilaterally oophorectomized for study of postcastration rise of follicle-stimulating hormone (FSH) and luteinizing hormone (LH). The animals were divided in two groups, control animals, which received vehicle, and experimental animals, which received intramuscularly 1 mg of a potent luteinizing hormone-releasing hormone (LHRH) inhibitory analog ([N-Ac-D-Trp1-3,D-p-Cl-phe2,D-Phe6,D-Ala10]-LH-RH) from the day of castration for 10 days. The controls showed significant elevations of FSH and LH 3 to 4 days after castration, but in the experimental animals the rise in gonadotropins was blocked until the LHRH antagonist administration was discontinued. The dynamics of gonadotropin elevation after the discontinuation of [N-Ac-D-Trp1-3,D-p-Cl-phe2,D-Phe6,D-Ala10]-LH-RH administration were similar to those observed in control animals after castration. The availability of a compound that selectively inhibits FSH and LH secretion in primates opens a new approach to contraception and for the treatment of conditions in which gonadotropin inhibition is desired.