Luteolysis induced by a luteinizing hormone-releasing hormone agonist is prevented by human chorionic gonadotropin.

The superactive stimulatory luteinizing hormone-releasing hormone (LRH) analogue D-Ser(TBU)6-EA10-LRh was administered intranasally to five healthy women in a daily dose of 600 microgram during two successive days of the mid-luteal phase. Both the basal serum progesterone levels and the length of the luteal phase were reduced, i.e. luteolysis occurred. Three women who were given additional treatment with human chorionic gonadotropin (HCG) in a daily intramuscular dose of 1500 IU for 10 days, had increased basal progesterone levels and a prolongation of the luteal phase. Thus, HCG prevented the luteolytic effect caused by the LRH agonist.