Dynamic changes in circulating inhibin levels during the luteal-follicular transition of the human menstrual cycle.
Dynamic changes in serum immunoreactive (ir) inhibin levels during the transition from the luteal to the follicular phase (luteal-follicular transition) were characterized during 3 consecutive cycles in 12 cycling women. Both spontaneous (first to second cycle) and GnRH antagonist-imposed premature luteolysis (second to third cycle) were evaluated. Serum FSH, LH, estradiol (E2), and progesterone (P4) levels were monitored daily by RIA for the entire study. Daily ir-inhibit levels were determined from 7 days before until 7 days after the onset of menses and from 4 days before to 10 days after the GnRH antagonist-induced bleeding by a heterologous RIA. During spontaneous luteolysis, ir-inhibin levels peaked 7 days before menses and declined in a linear fashion (r = -0.99) thereafter, reaching a sustained low level 1 day after the onset of menses. The decline of P4 and E2 levels appears to be coupled to that of ir-inhibin (r = 0.98 and r = 0.95, respectively). FSH levels showed an inverse pattern, with an acute elevation unaccompanied by LH, for 5 days before the onset of menses and reaching a plateau 2 days after. ir-Inhibin and FSH were negatively correlated (r = -0.87; P less than 0.0001). Increased LH levels did not occur until the day of menses and were negatively correlated with ir-inhibin (r = -0.50; P less than 0.05), but not E2 and P4. During the second cycle, at the midluteal phase luteolysis was induced by a single (50 micrograms/kg) im injection of a potent GnRH antagonist, [Ac-D2Nal,D4ClPhe2,D3Pal3,Arg5,DGlu6(AA),+ ++DAla10] GnRH; an acute decline of LH and FSH levels occurred, with maximal suppressions of 51% and 35%, respectively. ir-Inhibin levels decreased rapidly (40 +/- 2.8%) in parallel with E2 and P4 during the first 24 h and continued to decline for 4 days. The inverse relationship and time course of changes between FSH and ir-inhibin levels were similar to those of the spontaneous luteal-follicular transition. Six of the 12 subjects experienced partial reversal of luteolysis; the decline of ir-inhibin and the rise of FSH during the first 2 days were arrested for 4 days, which corresponded to the rebound increases in E2, P4, and LH. The subsequent fall of ir-inhibin was followed by a rise in FSH. Both the complete and incomplete luteolysis groups exhibited an orderly follicular maturation, LH surge, and luteal function during the ensuing cycle.(ABSTRACT TRUNCATED AT 400 WORDS)
Roseff
S J
SJ
Department of Reproductive Medicine, School of Medicine, University of California 92037.
Bangah
M L
ML
Kettel
L M
LM
Vale
W
W
Rivier
J
J
Burger
H G
HG
Yen
S S
SS
D000328:Adult; D004958:Estradiol / Q000097:blood; D005260:Female; D005640:Follicle Stimulating Hormone / Q000097:blood; D005498:Follicular Phase; D007987:Gonadotropin-Releasing Hormone / Q000031:analogs & derivatives / Q000494:pharmacology; D006801:Humans; D007265:Inhibins / Q000097:blood*; D008183:Luteal Phase; D007986:Luteinizing Hormone / Q000097:blood; D011374:Progesterone / Q000097:blood; D011863:Radioimmunoassay
C057805:LHRH, N-Ac-2-Nal(1)-4-Cl-Phe(2)-3-Pal(3)-Arg(5)-Glu(6)-AlaNH2(10)-; D007987:Gonadotropin-Releasing Hormone; D011374:Progesterone; D004958:Estradiol; D007265:Inhibins; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone