SUPPRESSION OF LUTEAL PROGESTERONE SECRETION IN THE STUMPTAILED MACAQUE BY AN ANTAGONIST ANALOGUE OF LUTEINIZING HORMONE RELEASING HORMONE

• Published in: Journal of endocrinology Vol. 104; no. 2; pp. R1 - R4
• Main Authors: FRASER, H. M, BAIRD, D. T, MCRAE, G. I, NESTOR, J. J, VICKERY, B. H
• Format: Journal Article
• Language: English
• Published: Colchester BioScientifica 01.02.1985; Portland Press
• Subjects: Animals; Biological and medical sciences; Corpus Luteum - metabolism; Depression, Chemical; Estrus; Female; Fundamental and applied biological sciences. Psychology; Gonadotropin-Releasing Hormone - antagonists & inhibitors; Hormone metabolism and regulation; Macaca; Mammalian female genital system; Pregnancy; Progesterone - blood; Progesterone - metabolism; Time Factors; Vertebrates: reproduction; Hypothalamohypophysoovarian axis; Menstrual cycle; Secretion; Peptide hormone; Monkey; Luteinizing hormon-releasing hormon; Ovary; Vertebrata; Mammalia; Female genital system; Primates; Corpus luteum; Antagonist; Progesterone; Sex steroid hormone
• ISSN: 0022-0795; 1479-6805
• DOI: 10.1677/joe.0.104R001

ABSTRACT The dependence of progesterone secretion from the corpus luteum on pituitary gonadotrophin was examined in the cyclic stumptailed macaque by studying the effects of a single s.c. injection of a potent LH releasing hormone (LHRH) antagonist, [N–Ac–D–Nal(2)1, D–pCl–phe2, D–Trp3, D–hArg(Et2)6, D–Ala10] LHRH. A dose of 100 μg antagonist/kg administered on days 9/10 of the luteal phase in three monkeys caused a marked temporary suppression of serum concentrations of LH and progesterone during the following 32 h but levels still remained detectable and after 2 days serum hormone concentrations returned to the normal luteal-phase range. When the same animals were treated with 300 μg antagonist/kg at the same period during a subsequent cycle, serum LH levels were close to or at the limits of detection of the bioassay for the next 48 h and progesterone concentrations declined steadily, reaching non-detectable values by 48 h. In two monkeys the progesterone levels remained suppressed and they menstruated prematurely; in the third monkey the progesterone concentration rose to just above baseline and menstruation occurred at the expected time. Administration of 300μg antagonist/ kg on days 6/7 of the luteal phase in a further three monkeys also suppressed progesterone concentrations but not to baseline values, and after 2 days a normal progesterone profile was regained. These results suggest that the corpus luteum of the stumptailed macaque is largely dependent on pituitary gonadotrophin support during the mid to late luteal phase.