title: Administration of human chorionic gonadotropin but not of luteinizing hormone-releasing hormone at pro-oestrus or late di-oestrus has a deleterious effect on pregnancy in the rat.
abstract: Embryonic and fetal mortality is studied, which is induced by human chorionic gonadotropin (hCG) and luteinizing hormone-releasing hormone (LHRH) given prior to ovulation. 5-day cyclic rats were injected with 20 IU hCG or with 1 microgram LHRH on day 3 of di-oestrus or on the day of pro-oestrus, and mated 4 h later. Autopsy was performed on day 3 or between days 13 and 18 of pregnancy. Advancement of ovulation by LHRH did not induce embryonic or fetal mortality. Administration of hCG at pro-oestrus or day 3 of di-oestrus induced a considerable mortality, which for the greater part occurred after day 3 of pregnancy but before implantation. This embryonic mortality could be prevented by anti-hCG serum given 21 h after hCG. It is speculated that embryonic mortality induced by hCG is caused by a relatively long-lasting disturbance of steroid metabolism, due to a long metabolic half-life of hCG. The disturbance of steroid metabolism as a possible cause of implantation failure is discussed.
mesh_terms: D000818:Animals; D006063:Chorionic Gonadotropin / Q000009:adverse effects*; D004031:Diestrus; D047108:Embryonic Development; D005260:Female; D005328:Fetal Viability / Q000187:drug effects*; D007987:Gonadotropin-Releasing Hormone / Q000494:pharmacology; D010060:Ovulation / Q000187:drug effects; D011247:Pregnancy; D011359:Proestrus; D051381:Rats; D011919:Rats, Inbred Strains
chemical_list: D006063:Chorionic Gonadotropin; D007987:Gonadotropin-Releasing Hormone