Exogenous versus endogenous pulses of luteinizing hormone-releasing hormone and secretory patterns of gonadotropins.

OBJECTIVE

Does an exogenously administered regimen of luteinizing hormone-releasing hormone (LH-RH) pulses override endogenous LH-RH?

DESIGN

Pulses of LH-RH were given intravenously during 1 week with intervals of 90 (n = 5) or 120 minutes (n = 5). Before, during, and after treatment serial plasma luteinizing hormone (LH) and follicle-stimulating hormone (FSH) patterns and pituitary responsiveness to LH-RH were estimated.

PATIENTS

Women with virtual absence of gonadal function (postmenopause, gonadal dysgenesis, and premature menopause).

RESULTS

During treatment with the 90-minute interval, no LH pulses that were not related to injections of LH-RH were observed. Two spontaneous LH pulses were observed during treatment with the 120-minute interval. Immediately after treatment, a lowered incidence of spontaneous LH pulses was seen of 3 pulses/6 h if LH-RH had been given every 90 minutes and to 1.5 pulses/6 h after the 120-minute interval treatment. Gonadotropin responses to 100 micrograms of LH-RH were attenuated during treatment but recovered within 48 hours after discontinuation of treatment.

CONCLUSIONS

(1) Exogenously administered LH-RH can override endogenous LH-RH or its effects on the release of LH in women with hypergonadotropic hypogonadism; (2) during pulsatile LH-RH treatment desensitization of the pituitary occurs to some degree; and (3) immediately after cessation of treatment with pulsatile LH-RH, spontaneous LH pulses are present but with a significantly lower incidence.