Luteinizing hormone-releasing hormone versus human chorionic gonadotropin: differential effect on the development of ovulatory refractoriness and antibodies.

Cyclic intramuscular injections of 25 IU of human chorionic gonadotropin (HCG) at 3-week intervals induced ovulatory refractoriness and HCG antibodies after five to eight treatment cycles. Two of fifty rabbits failed to ovulate following two successive injections of luteinizing hormone-releasing hormone (LH-RH); however, no LH-RH antibodies were detected in the sera of these two animals, suggesting that these observations were due to chance alone. Thus, 0.5 mug of LH-RH injected intramuscularly at 3-week intervals did not induce ovulatory refractoriness or antibody formation after as many as 18 successive treatment cycles.