title: Acute effects of intravenous infusion of 17beta-estradiol and 17alpha-hydroxyprogesterone on gonadotropin release.
abstract: The normal midcycle surge of luteinizing hormone (LH), an approximately 10-fold increase, and a smaller surge of follicle-stimulating hormone (FSH) are preceded by peaks in serum estradiol (E2) and 17alpha-hydroxyprogesterone (17-P). The elevation in E2 is thought to be the important trigger mechanism for the LH surge. The possibility that the preovulatory elevation in 17-P may by itself, or combined with E2, be the trigger mechanism was investigated. E2 ans 17-P, alone and combined, were infused to mimic late follicular-phase blood concentrations in postmenopausal women pretreated with E2. This produced 1.6- to 4.6-fold increases in serum LH and lesser increases in serum FSH 24 hours after infusion. Thus, the normal ovulatory surge of gonadotropins could not be reproduced by infusions of 17-P or E2, or both. Infusion with 17-P appeared to stimulate LH release and did not augment or inhibit the effect of E2 on gonadotropin release.
mesh_terms: D004958:Estradiol / Q000008:administration & dosage* / Q000494:pharmacology; D005260:Female; D005640:Follicle Stimulating Hormone / Q000378:metabolism*; D006801:Humans; D006908:Hydroxyprogesterones / Q000008:administration & dosage* / Q000494:pharmacology; D007263:Infusions, Parenteral; D007986:Luteinizing Hormone / Q000378:metabolism*; D008598:Menstruation; D008875:Middle Aged; D013268:Stimulation, Chemical
chemical_list: D006908:Hydroxyprogesterones; D004958:Estradiol; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone