Decreased inhibin tone and increased activin A secretion characterize reproductive aging in women

• Published in: Fertility and sterility Vol. 71; no. 4; p. 658
• Main Authors: Santoro, N, Adel, T, Skurnick, J H
• Format: Journal Article
• Language: English
• Published: United States 01-04-1999
• Subjects: Activins; Adult; Aging; Estradiol - blood; Female; Follicle Stimulating Hormone - blood; Follicular Phase - blood; Humans; Inhibins - blood; Luteal Phase - blood; Luteinizing Hormone - blood; Middle Aged; Progesterone - blood; Quality Control
• ISSN: 0015-0282
• DOI: 10.1016/S0015-0282(98)00529-9

We hypothesized that the increased FSH noted in older reproductive-aged women is due to both decreased inhibin and increased activin A secretion.
Comparative clinical study.
An academic research center.
Five cycling women, aged 43 to 47, were compared to five midreproductive women, aged 19 to 38.
Specimens taken every 2 to 3 days were assayed for inhibin A and B and activin A.
Integrated concentrations of inhibin A, inhibin B, and activin A in the follicular phase, luteal phase, and whole cycle.
Follicular inhibin B was reduced in older versus younger women (504 +/-82 versus 748+/-72 total pg). Luteal inhibin A was reduced in older versus younger women (668 +/-72 versus 1152+/-216 total pg). Activin A was elevated throughout the cycle of older versus younger women, without within-cycle fluctuations (21+/-2 versus 11+/-1 total ng).
Lack of restraint by inhibin A and inhibin B contributes to the FSH rise associated with reproductive aging. This loss of restraint occurs in a tandem fashion, with inhibin B reduction before ovulation and inhibin A reduction after ovulation. Activin A may also play an endocrine role in maintaining elevated FSH in older reproductive-aged women.