Interrelationships between ovarian and pituitary hormones in ovulatory menstrual cycles across reproductive age.
BACKGROUND
Ovarian hormones regulate pituitary gonadotropin secretion across the menstrual cycle via negative and positive feedback mechanisms. The contribution of individual hormones is complex and is a continuing area of research.


OBJECTIVE
The aim of the study was to identify relationships between LH/FSH and estradiol, progesterone, inhibin A, inhibin B, and anti-Mullerian hormone (AMH) in ovulatory menstrual cycles across reproductive age.


METHODS
Serum ovarian and pituitary hormones were studied in a group of young (<35 yr; n = 21) and older (>45 yr; n = 55) women. The slopes of the regression lines relating the ovarian and pituitary hormones were determined by multiple linear regression analysis and expressed with 95% confidence intervals for each ovarian hormone, with FSH and LH as independent variables. Both simultaneous and delayed (time lagged) relationships were examined.


RESULTS
Clear associations were evident for the lagged prediction of FSH, with significant negative associations being evident with inhibin B and AMH in the follicular phase and with estradiol, inhibin B, progesterone, and AMH in the luteal phase. For the lagged prediction of LH, significant positive and negative associations were observed with estradiol and inhibin B, respectively, in the follicular phase and a negative association with progesterone and inhibin B in the luteal phase.


CONCLUSIONS
It is concluded that in the follicular phase, inhibin B is a major feedback regulator of FSH and may also be a negative feedback regulator of LH. AMH may be indirectly involved in FSH regulation.
Prince Henry's Institute of Medical Research, P.O. Box 5152, Clayton, Victoria 3168, Australia. david.robertson@princehenrys.org
David M
DM
Robertson
Georgina E
GE
Hale
Damien
D
Jolley
Ian S
IS
Fraser
Claude L
CL
Hughes
Henry G
HG
Burger
D000328:Adult; D054304:Anti-Mullerian Hormone / Q000097:blood; D004958:Estradiol / Q000097:blood; D025461:Feedback, Physiological; D005260:Female; D005640:Follicle Stimulating Hormone / Q000097:blood; D042341:Gonadal Hormones / Q000097:blood*; D006801:Humans; D007265:Inhibins / Q000097:blood; D007986:Luteinizing Hormone / Q000097:blood; D008597:Menstrual Cycle / Q000097:blood*; D008875:Middle Aged; D010907:Pituitary Hormones / Q000097:blood*; D011374:Progesterone / Q000097:blood
D042341:Gonadal Hormones; D010907:Pituitary Hormones; C422362:inhibin A; C422364:inhibin B; D011374:Progesterone; D004958:Estradiol; D007265:Inhibins; D054304:Anti-Mullerian Hormone; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone