Levels of Luteinizing Hormone (LH), Follicle-Stimulating Hormone, and 17β-Estradiol in Response to D-Trp6-LH-Releasing Hormone During Different Phases of the Menstrual Cycle in Normal Women

The response of luteinizing hormone (LH), follicle-stimulating hormone (FSH), and 17 β-estradiol to d-Trp6-LH-releasing hormone (LH-RH) was studied in 34 normal women. This long-acting, superactive analog was given by several routes of administration (intravenously, intramuscularly, and by continuous intravenous infusion) and in increasing doses of 1 to 50μg in three phases of the menstrual cycle: late folliclular (8th to 10th days of the cycle), preovulatory (11th to 13th days of the cycle), and ovulatory (14th day of the cycle). In all phases of the cycle, LH and FSH responses to the analog increased significantly (P<0.05) from 60minutes as compared with basal levels, with a duration of at least 8hours. After the intravenous administration of 10μg of d-Trp6-LH-RH, 17 β-estradiol reached a statistically significant value (P<0.05) at 8hours. During the follicular phase, d-Trp6-LH-RH was 40 and 21 times more potent than LH-RH in stimulating the release of LH and FSH, respectively. When 10μg of the analog was administered by continuous intravenous infusion, the kinetics of the LH and FSH response in the ovulatory phase were different from responses in the follicular and preovulatory phases, with a faster release of gonadotropins at 2hours in comparison with that in the other phases. In addition, the total amounts of LH and FSH released were twice as great in the ovulatory phase as in the two other phases. The release of LH and FSH in women was nearly always statistically greater (P<0.05) in comparison with that observed in men. The high potency and prolonged duration of action of this compound suggest its potential usefulness for increasing estradiol levels and for stimulation of ovulation in women