Progesterone alters the pituitary response to luteinizing hormone releasing hormone in postmenopausal women previously treated with estradiol.
The effect of luteinizing hormone-releasing hormone (LHRH) on LH release was studied in 5 menopausal women injected with progesterone. Each patient received 2 x 100 micrograms doses of LHRH administered intravenously 120 minutes apart under the following conditions: without any previous treatment (test 1); 16 hours after intramuscular injection of 10 mg progesterone (test 2); after 3-4 weeks of oral treatment with 50 micrograms/day of ethinyl estradiol (EE2) (test 3); 16 hours after intramuscular injection of 10 mg progesterone following treatment with 50 micrograms/day oral EE2 for 3-4 weeks (test 4). The interval between tests was at least 1 month. Progesterone decreased the total plasma hormonal increment (PHIt) of hypogonadal women, with a reduction in plasma hormonal increment both after the 1st stimulus (PHI1) and after the 2nd stimulus (PHI2), whereas estradiol increased PHIt, mainly due to an increase of PHI2. The administration of progesterone to hypogonadal women previously treated with EE2 maintained the increased PHIt caused by the latter, but not owing to a greater increase in PHI1.
Silva de Sá
M F
MF
Department of Gynecology and Obstetrics, University of São Paulo, Brazil.
Shibasaki
H I
HI
Ferriani
R A
RA
de Moura
M D
MD
D004347:Drug Interactions; D004997:Ethinyl Estradiol / Q000494:pharmacology*; D005260:Female; D007987:Gonadotropin-Releasing Hormone / Q000494:pharmacology*; D006801:Humans; D007986:Luteinizing Hormone / Q000378:metabolism; D008593:Menopause / Q000187:drug effects* / Q000378:metabolism; D008875:Middle Aged; D010902:Pituitary Gland / Q000187:drug effects* / Q000378:metabolism; D011374:Progesterone / Q000494:pharmacology*
D007987:Gonadotropin-Releasing Hormone; D004997:Ethinyl Estradiol; D011374:Progesterone; D007986:Luteinizing Hormone