Dynamic Changes in Circulating Inhibin Levels during the Luteal-Follicular Transition of the Human Menstrual Cycle *

Abstract

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)

Serum Immunoreactive Inhibin Levels in Polycystic Ovarian Disease (PCOD) and Hypogonadotropic Amenorrhea.

“…In addition, Fraser et al [23] reported that anti-inhibin serum administration to the stump-tailed macaque in the mid-luteal phase did not have significant effects on serum FSH, but they found a significant increase in serum FSH in the early follicular phase of the following cycle. The report of Fraser et al also indicates that inhibin is not the sole factor in suppressing FSH secretion during the luteal phase [24] but probably plays an important role in the selective inhibition of FSH release, particularly in the luteal-follicular transition phase where circulating progesterone and E2 are quite low [5]. Because PCOD patients have no cycles and their pituitary gland is chronically exposed to slightly increased inhibin, it is likely that inhibin is involved in modulating FSH secretion in women with PCOD.…”

“…We collected control samples on days 2 to 5 from the onset of menstruation because it had been found that the lowest inhibin levels are detected on day 2 after the onset of menstruation [5], while Buckler et al, collected control samples on days -9 to -7 based on the midcycle gonadotropin surge. Our results indicate that serum IR-inhibin levels in PCOD women are significantly higher than those in normal women in the early stage of the menstrual cycle, but it still remained nuclear whether the inhibin concentration detected in PCOD plays a significant role in selective inhibition of FSH secretion.…”

“…With the development of a radioimmunoassay of inhibin with sufficient sensitivity [3,4], several studies demonstrated changes in serum immunoreactive (IR)-inhibin during normal menstruation [4][5][6] and stimulated cycles [7,8], but little has been shown about basal inhibin levels in patients with ovulatory disorders. Many studies thus far reported failed to show an inverse correlation between the two hormones, and it is still controversial whether inhibin is involved in the discordant gonadotropin secretion by selective inhibition of FSH release in women with polycystic ovarian disease (PCOD) [9].…”

Short Communication: FSH Time-Concentration Profiles Before and After Administration of 0.25 mg Cetrorelix in the GnRH-Antagonist Multiple-Dose Protocol for Ovarian Hyperstimulation

“…Both estradiol and inhibin are longknown potent suppressors of FSH secretion, leading to a progressive decline of FSH secretion during the mid to late follicular phase. In contrast, corresponding circulating LH levels exhibit a progressive increasing trend, ultimately leading to ovulation (4).…”

Do women's preferences for symmetry change across the menstrual cycle?

“…This applies particularly to females, whose preference for symmetry could vary across the menstrual cycle such that it will be lower during the low-fertility (menstrual and luteal) phases, when luteinizing hormone is low, and higher during the high-fertility (ovulatory) latefollicular phase, when luteinizing hormone is high (e.g., Roseff et al, 1989). Normally, fertility (the probability of conception) is high between Days 10 and 17 of the cycle, and highest 2 days prior to ovulation, but drops substantially 1 day after ovulation (Dunson, Baird, Wilcox, & Weinberg, 1999).…”