Periovulatory Hormonal Dynamics: Relationship of Immunoassayable Gonadotropins and Ovarian Steroids to the Bioassayable Luteinizing Hormone Surge in Rhesus Monkeys

Robert S. Schenken, Lawrence B. Werlin, Robert F. Williams, Thomas J. Prihoda, Gary D. Hodgen

Research output: Contribution to journalArticlepeer-review

24 Scopus citations

Abstract

The relationship between ovarian steroids and LH during the midcycle gonadotropin surge is controversial. Recent demonstration of temporal and quantitative differences in immunoassayable LH (I-LH) and bioassayable LH (B-LH) at midcycle have further clouded this issue. To evaluate the relationship of I-LH, FSH, and ovarian steroids to the onset of the midcycle B-LH surge, blood samples were obtained from five chronically catheterized rhesus monkeys at 2-h intervals for 5-6 days. The plasma was assayed for FSH, LH, 17β-estradiol (E2), progesterone (P4), and 17±-hydroxyprogesterone (17-OHP) by RIA and for LH by a rat interstitial cell testosterone in vitro bioassay. The initiation of the B-LH surge served as time zero (t0) for the temporal analysis of changes in plasma hormone levels. The I-LH and FSH surges were initiated 6.4 ± 2.2 h (mean ±SEM) and 5.2 ± 1.9 h, respectively, after the onset of the B-LH surge. Although the duration of the ascending limb of the surge was similar for B-LH, I-LH, and FSH, the mean ± SEM total duration of the B-LH surge (34.5 ±3.5 h) was significantly longer (P <0.025) than those of I-LH (24.4 ± 5.0 h) and FSH (27.6 ± 2.3 h). Before the onset of the B-LH surge (t0 - 4 h), the ratio of B-H to I-LH was unity; however, during the acme of gonadotropin secretion (t0 + 12- 16 h), the B-LH to I-LH ratio approached 6:1. Doubling times for B-LH, I-LH, and FSH were similar during the ascending phase of the surge. Plasma E2 concentrations increased continuously from t0 - 40 h to t0, with (a mean ±SEM doubling time of 32.6 ±4.7 h. Peak E2 concentrations occurred within 6 h after the onset of the B-LH surge. Plasma P4 concentrations began to increase at t0 - 6 h in four monkeys and at t0 in one monkey. Plasma P4 concentration plateaued from t0 to t0 + 24 h, then increased rapidly, with a mean ± SEM doubling time of 20.5 ± 2.9 h. Although there were significant individual variations in plasma 17-OHP concentrations, a definite increase in 17-OHP occurred by t0 - 10 h, and peak concentrations occurred at t0 + 1 h. Plasma 17-OHP concentrations infsequently declined and remained at a nadir until t0 + 68 h, at which time they began to increase, with a mean ± SEM doubling time of 30.9 ± 2.6 h. These data demonstrate that the midcycle B-LH surge is qualitatively and quantitatively distinct from that of I-LH; further, P4 and 17-OHP may facilitate the onset of both B-LH and I-LH surges.

Original languageEnglish (US)
Pages (from-to)886-890
Number of pages5
JournalJournal of Clinical Endocrinology and Metabolism
Volume60
Issue number5
DOIs
StatePublished - May 1985

ASJC Scopus subject areas

  • Endocrinology, Diabetes and Metabolism
  • Biochemistry
  • Endocrinology
  • Clinical Biochemistry
  • Biochemistry, medical

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