Serum hormone levels during a post-implantation LH-RH induced luteolysis in the rat.
Daily administration of LH-RH (100 micrograms sc at 0900 and 1500 h) to rats over day 7-12 (D7-12) of pregnancy induced reovulation by D9 and a sustained decrease in uterine:fetal weight and vaginal bleeding by 0600 h on D10 of pregnancy. Serum hormone levels determined at 0600, 1200, and 2000 h over D7-12 of pregnancy revealed that luteinizing hormone (LH) was significantly elevated after each administration of LH-RH, while prolactin (PRL) was not significantly altered in any systematic fashion. An acute decline in serum progesterone at 2000 h on D7-9 following LH-RH administration was not sustained until after 0600 h on D10 when serum 20 alpha-dihydroprogesterone (20 alpha-hydroxy-4-pregnen-3-one, 20 alpha-DHP) in LH-RH treated animals rose significantly above control (2000 h, D10) and remained elevated throughout D11-12. Progesterone and 20 alpha-DHP values were reflected morphologically after D10 as the corpora lutea of LH-RH treated rats underwent luteolysis. A peak in serum estradiol levels in control animals was observed at 0600 h on D9. Serum estradiol-17 beta levels in LH-RH treated animals were similar to control except at 2000 h on D8 and D12 when LH-RH induced a significant increase. These observations suggest that subsequent to implantation in the rat, the temporal sequence of a decrease in progesterone secretion, luteolysis and pregnancy failure in response to LH-RH does not result from an increase in estradiol secretion attendant to reovulation.
D004092:20-alpha-Dihydroprogesterone / Q000097:blood*; D000818:Animals; D003338:Corpus Luteum / Q000187:drug effects*; D004958:Estradiol / Q000097:blood*; D005260:Female; D005333:Fetus / Q000187:drug effects; D007987:Gonadotropin-Releasing Hormone / Q000494:pharmacology*; D007986:Luteinizing Hormone / Q000097:blood*; D009929:Organ Size; D010060:Ovulation / Q000187:drug effects; D011247:Pregnancy; D011374:Progesterone / Q000031:analogs & derivatives* / Q000097:blood*; D011388:Prolactin / Q000097:blood*; D051381:Rats; D013997:Time Factors; D014599:Uterus / Q000187:drug effects
D004092:20-alpha-Dihydroprogesterone; D007987:Gonadotropin-Releasing Hormone; D011374:Progesterone; D004958:Estradiol; D011388:Prolactin; D007986:Luteinizing Hormone