title: Effect of 20 alpha-dihydroxyprogesterone on the estrogen-induced bioactive luteinizing hormone surge in ovariectomized monkeys.
abstract: Progestins facilitate estrogen induction of the preovulatory luteinizing hormone (LH) surge. A biologically weaker progestin, 20 alpha-dihydroxyprogesterone, is reportedly increased at midcycle, but the importance of 20 alpha-dihydroxyprogesterone in regulating LH release has not been systematically studied. We therefore evaluated the effect of 2 doses of 20 alpha-dihydroxyprogesterone on the bioactive LH surge onset in ovariectomized monkeys. Chronically cannulated monkeys (n = 10) received estradiol (E2) benzoate (50 micrograms/kg) with and without subsequent 20 alpha-dihydroxyprogesterone injections (50 micrograms/kg, n = 3 and 100 micrograms/kg, n = 3). Blood was collected every 15 minutes over preselected intervals and the plasma assayed for bioactive LH and gonadal steroids. Low-dose 20 alpha-dihydroxyprogesterone administration resulted in periovulatory peripheral 20 alpha-dihydroxyprogesterone levels and did not advance the bioactive LH surge onset. In contrast, high-dose 20 alpha-dihydroxyprogesterone resulted in supraphysiological 20 alpha-dihydroxyprogesterone levels, slight increases in progesterone levels, and significant advancement of the surge over E2 benzoate treatment alone. We conclude that periovulatory levels of 20 alpha-dihydroxyprogesterone do not play a role in modulating the estrogen-induced bioactive LH surge.
authors: Department of Obstetrics and Gynecology, University of Texas Health Science Center, San Antonio 78284.
authors: R S
authors: RS
authors: Schenken
authors: R F
authors: RF
authors: Williams
authors: G D
authors: GD
authors: Hodgen
mesh_terms: D000818:Animals; D004305:Dose-Response Relationship, Drug; D004958:Estradiol / Q000494:pharmacology*; D005260:Female; D006908:Hydroxyprogesterones / Q000494:pharmacology*; D007986:Luteinizing Hormone / Q000097:blood* / Q000502:physiology; D008252:Macaca fascicularis; D008253:Macaca mulatta; D010052:Ovariectomy
chemical_list: D006908:Hydroxyprogesterones; D004958:Estradiol; D007986:Luteinizing Hormone