title: Age-related analysis of inhibin A, inhibin B, and activin a relative to the intercycle monotropic follicle-stimulating hormone rise in normal ovulatory women.
abstract: Previous studies have reported that the monotropic rise in FSH in older women is associated with decreased inhibin B and/or A levels and increased levels of activin A. Whereas most investigators have found decreased follicular-phase inhibin B, the roles of inhibin A and activin A as modulators of the FSH rise are unclear. The objectives of this study were to determine whether deficiencies in circulating levels of inhibin A, inhibin B, and/or activin A exist during the intercycle interval in ovulatory older (age, 40-45 yr; n = 16), compared with younger women (age, 20-25 yr; n = 13). Blood samples were obtained daily throughout one menstrual cycle and the follicular phase of the subsequent cycle and were analyzed for LH, FSH, estradiol, inhibin A and B, and activin A. Despite significant FSH elevation, no deficiencies in inhibin A, activin A, or estradiol were detected in older subjects. In fact, inhibin A was significantly higher in older participants during the intercycle phase (P = 0.01), whereas inhibin B was significantly lower. Thus, the monotropic rise in FSH does not appear to result from changes in inhibin A or activin A, supporting the concept that inhibin B plays a critical role in mediating the FSH rise in older women.
authors.affiliation: Department of Obstetrics and Gynecology, University of Washington, Seattle, Washington 98105, USA. nklein@u.washington.edu
authors.forename: Nancy A
authors.initials: NA
authors.lastname: Klein
authors.forename: Brenda S
authors.initials: BS
authors.lastname: Houmard
authors.forename: Karl R
authors.initials: KR
authors.lastname: Hansen
authors.forename: Teresa K
authors.initials: TK
authors.lastname: Woodruff
authors.forename: Patrick M
authors.initials: PM
authors.lastname: Sluss
authors.forename: William J
authors.initials: WJ
authors.lastname: Bremner
authors.forename: Michael R
authors.initials: MR
authors.lastname: Soules
mesh_terms: D028341:Activins / Q000097:blood*; D000328:Adult; D000375:Aging / Q000378:metabolism*; D015415:Biomarkers; D004958:Estradiol / Q000097:blood; D005260:Female; D005640:Follicle Stimulating Hormone / Q000097:blood*; D005498:Follicular Phase / Q000378:metabolism*; D006801:Humans; D028322:Inhibin-beta Subunits / Q000097:blood*; D007265:Inhibins / Q000097:blood*; D007986:Luteinizing Hormone / Q000097:blood; D008875:Middle Aged; D011374:Progesterone / Q000097:blood
chemical_list: D015415:Biomarkers; C422405:activin A; C422362:inhibin A; C422364:inhibin B; D028341:Activins; D011374:Progesterone; D004958:Estradiol; D007265:Inhibins; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone; D028322:Inhibin-beta Subunits