Effect of ghrelin on gonadotrophin secretion in women during the menstrual cycle.
BACKGROUND
It has been suggested that ghrelin may affect reproduction in animals by decreasing pituitary LH secretion. The role of ghrelin on LH secretion in women has not been investigated. Our aim was to assess the effect of ghrelin administration on basal and GnRH-induced LH secretion during the menstrual cycle.


METHODS
Normally cycling women (n = 10) received on Day 3 of three consecutive cycles a single bolus i.v. of either ghrelin (1 microg/kg, cycle 1) or GnRH (100 microg, cycle 2) or GnRH plus ghrelin (cycle 3). In cycle 1, ghrelin was also injected in late follicular and mid-luteal phase of the cycle. Saline was injected in a preceding cycle (cycle 1, control). Blood samples were taken before drugs or saline injection (time 0) as well as at -15, 15, 30, 45, 60, 75, 90 and 120 min.


RESULTS
Plasma ghrelin levels increased rapidly, peaking at 15 or 30 min (P < 0.001), then decreased steadily, approaching pre-injection levels at 120 min. Serum FSH, LH, estradiol and progesterone levels remained unchanged. The stimulating effect of GnRH on LH and FSH secretion was unaffected by ghrelin injection. In contrast to saline, ghrelin stimulated a significant increase in growth hormone levels.


CONCLUSIONS
Under these experimental conditions, our results demonstrate for the first time the inability of a bolus of ghrelin to affect basal and GnRH-induced LH and FSH secretion. It is suggested that ghrelin does not play a major physiological role in gonadotrophin secretion in women.
Messini
Christina I
CI
Department of Obstetrics and Gynaecology, University of Thessalia 41110, Larissa, Greece.
Dafopoulos
Konstantinos
K
Chalvatzas
Nektarios
N
Georgoulias
Panagiotis
P
Messinis
Ioannis E
IE
D000328:Adult; D004958:Estradiol / Q000097:blood; D005260:Female; D005640:Follicle Stimulating Hormone / Q000097:blood / Q000378:metabolism*; D005498:Follicular Phase / Q000097:blood / Q000187:drug effects; D054439:Ghrelin / Q000008:administration & dosage* / Q000097:blood / Q000502:physiology; D007987:Gonadotropin-Releasing Hormone / Q000008:administration & dosage; D006801:Humans; D008183:Luteal Phase / Q000097:blood / Q000187:drug effects; D007986:Luteinizing Hormone / Q000097:blood / Q000378:metabolism*; D008597:Menstrual Cycle / Q000097:blood* / Q000187:drug effects* / Q000502:physiology; D011374:Progesterone / Q000097:blood; D055815:Young Adult
D054439:Ghrelin; D007987:Gonadotropin-Releasing Hormone; D011374:Progesterone; D004958:Estradiol; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone