title: Regression of induced corpora lutea in mature cyclic gilts by human chorionic gonadotropin.
abstract: This study was conducted to determine whether chronic hCG treatment would cause regression of induced corpora lutea (CL) in mature cyclic gilts. Thirty-two mature gilts that had displayed one or more estrous cycles of 18 to 22 d were used. Sixteen gilts were hysterectomized (HYSTX) on d 6 to 9 (d 0 = onset of estrus) and their CL were marked with charcoal (spontaneous group). Sixteen gilts (induced group) were injected with 1,500 IU of pregnant mare's serum gonadotropin (PMSG) on d 6 and 500 IU of hCG on d 9 (day of hCG = d 0 of the induced cycle). Ovulation was assumed to occur on d 2 of the induced cycle. Induced gilts were HYSTX on d 8 to 9 (d 17 to 18 of the original spontaneous cycle) and their CL were marked with charcoal. Only gilts (n = 14) in which induced CL were present and in which the original CL had regressed were then subjected to treatment with saline or hCG. From d 10 to 29, gilts with spontaneous CL were injected daily with 500 IU of hCG (n = 8) or saline (n = 8). From d 10 to 29 of the induced cycle, induced gilts were injected daily with 500 IU of hCG (n = 6) or saline (n = 8). Jugular blood samples were collected every other day from all gilts beginning on the 1st d of daily hCG treatment and quantified for estradiol and progesterone by RIA. On the day after the last hCG injection, the number of charcoal-marked CL and charcoal-marked corpora albicantia (CA) were determined.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Animal and Dairy Science Department, University of Georgia, Athens 30602.
authors.forename: G B
authors.initials: GB
authors.lastname: Rampacek
authors.forename: R R
authors.initials: RR
authors.lastname: Kraeling
authors.forename: C R
authors.initials: CR
authors.lastname: Barb
authors.forename: C E
authors.initials: CE
authors.lastname: Estienne
authors.forename: M J
authors.initials: MJ
authors.lastname: Estienne
mesh_terms: D000818:Animals; D006063:Chorionic Gonadotropin / Q000494:pharmacology*; D003338:Corpus Luteum / Q000187:drug effects* / Q000502:physiology; D004958:Estradiol / Q000097:blood; D005260:Female; D007044:Hysterectomy / Q000662:veterinary; D011374:Progesterone / Q000097:blood; D013552:Swine / Q000502:physiology*
chemical_list: D006063:Chorionic Gonadotropin; D011374:Progesterone; D004958:Estradiol