FSH and LH responses to GnRH after ovariectomy in postmenopausal women.
OBJECTIVE
Whether the postmenopausal ovary is still playing a role in the control of gonadotrophin secretion in response to GnRH has not been investigated. The aim of the present study was to test this hypothesis by examining changes in basal and GnRH-induced gonadotrophin secretion in postmenopausal women after bilateral ovariectomy.


METHODS
The responses of LH and FSH to GnRH [10 microg intravenously (i.v.)] were investigated in postmenopausal women from 2 days before to 8 days after total abdominal hysterectomy plus bilateral ovariectomy.


METHODS
Nine postmenopausal women aged 52-67 years and between 5 and 15 years after menopause. In all cases the ovaries were histologically normal.


METHODS
Pituitary responses to GnRH were calculated every 12-24 h as the net increases in LH (DeltaLH) and FSH (DeltaFSH) at 30 min above the basal values. Basal values of oestradiol (E2) and testosterone were also measured.


RESULTS
Basal values of FSH showed a significant decrease on postoperative days 2 (P < 0.01) and 8 (P = 0.03) as compared to day 0, while at the same time points after the operation LH values were marginally lower than on day 2 (P = 0.05). Serum E2 values showed a gradual increase up to postoperative day 1 (P = 0.04) and a gradual decline thereafter. Basal testosterone concentrations decreased gradually and significantly after ovariectomy and were significantly lower on day 8 than on day 0 (P < 0.01). DeltaFSH and DeltaLH responses to GnRH did not change significantly with time. A temporary increase at 12 h after the operation was not significant.


CONCLUSIONS
These results demonstrate for the first time that the removal of the ovaries in postmenopausal women does not affect GnRH-induced gonadotrophin secretion in the short term. It is suggested that the postmenopausal ovary is not a dominant regulator of hypothalamic-pituitary interactions.
Dafopoulos
K C
KC
Department of Obstetrics and Gynaecology, University of Thessalia, Larissa, Greece.
Kotsovassilis
C P
CP
Milingos
S D
SD
Kallitsaris
A T
AT
Georgadakis
G S
GS
Sotiros
P G
PG
Messinis
I E
IE
D000368:Aged; D004958:Estradiol / Q000097:blood; D005260:Female; D005640:Follicle Stimulating Hormone / Q000097:blood*; D007987:Gonadotropin-Releasing Hormone; D006801:Humans; D007986:Luteinizing Hormone / Q000097:blood*; D008875:Middle Aged; D010052:Ovariectomy; D010902:Pituitary Gland / Q000187:drug effects*; D017698:Postmenopause / Q000378:metabolism*; D011184:Postoperative Period; D013739:Testosterone / Q000097:blood
D007987:Gonadotropin-Releasing Hormone; D013739:Testosterone; D004958:Estradiol; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone