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Effects of chronic GnRH analogue administration on gonadotrophin and α‐subunit secretion in post‐menopausal women
Author(s) -
Oppenheim Daniel S.,
Bikkal Helen,
Crowley William F.,
Klibanskl Anne
Publication year - 1992
Publication title -
clinical endocrinology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.055
H-Index - 147
eISSN - 1365-2265
pISSN - 0300-0664
DOI - 10.1111/j.1365-2265.1992.tb02265.x
Subject(s) - endocrinology , medicine , agonist , luteinizing hormone , hormone , receptor
OBJECTIVE To investigate in detail the regulation of LH, FSH, and α‐subunit secretion by a GnRH agonist analogue under physiological conditions of gonadotrophin elevation. SUBJECTS Six normal healthy post‐menopausal women. DESIGN Subjects were given D‐Trp 6 ‐Pro 9 ‐Net‐GnRH (GnRHa), 32 μg/kg, subcutaneously, dally for 24 days. On days 1, 2, 3, 4, 7, 11, 14, 17, 21, and 24, blood samples before and after GnRHa injection were taken. Sampling was continued off GnRHa twice a week for 4 weeks and then on days 66, 76, and 98. GnRH tests (100 μg l. v.) were performed on days 0, 24, and 98. MEASUREMENTS All serum samples were analysed for LH, FSH, and α‐subunit levels. RESULTS LH and FSH levels reached a maximum on day 2 after which there was a steady decline to day 24. LH did not begin to rise again until day 44 (20 days off GnRHa), then rose steadily. FSH began to rise earlier, on day 34 (10 days off GnRHa). α‐Subunit levels also showed maximum elevation on day 2 but remained equally elevated throughout the period of GnRHa administration and then fell rapidly to baseline by day 34. LH, FSH, and α‐subunit responses to i. v. GnRH were absent on day 24 and were equivalent to baseline on day 98. CONCLUSIONS We conclude that there is a striking dissociation in the regulation of gonadotrophin and α‐subunit secretion in response to GnRHa in normal post‐menopausal women. Gonadotrophin secretion is profoundly suppressed during GnRHa administration and recovers only after a long delay post‐treatment, while α‐subunit is markedly stimulated and recovers rapidly. The difference between this pattern and that seen in patients with pituitary tumours could be useful for diagnosis.