title: Effect of a gonadotrophin-releasing hormone antagonist on luteinising hormone secretion and early pregnancy in gilts.
abstract: The aims of the present study were: (1) to determine the duration of suppression of luteinising hormone (LH) following a single treatment with a gonadotrophin-releasing hormone (GnRH) antagonist (BIM-21009; Biomeasure) at a dose of 100 microg kg(-1); (2) to block LH pulses only for certain days of pregnancy; and (3) to determine the period of early pregnancy most susceptible to suppression of LH. Three groups of gilts were injected with 100 microg kg(-1) on Day 16 (n = 5), 14 (n = 6) or 19 (n = 4) of pregnancy. Blood for LH analysis was collected at 20-min intervals for 12 h on the day before treatment and during varying stages of early pregnancy. Blood for progesterone analysis was collected daily and development of pregnancy was followed using real-time ultrasound. Prior to treatment, gilts had 2.6 +/- 0.7 LH pulses per 12 h. The GnRH antagonist abolished LH pulses for a period of 2.7 +/- 1.8 days and, thereafter, suppressed the resumed LH pulses (P < 0.05). Pregnancy was disrupted in three pigs (20%) with a mean treatment-to-abortion period of 4.7 days concurrent with a mean treatment-to-progesterone decline interval of 4.3 days. In a proportion of pigs, short-term LH suppression may cause early disruption of pregnancy.
authors.affiliation: University of Helsinki, Faculty of Veterinary Medicine, Department of Clinical Veterinary Sciences, Pohjoinen Pikatie 800, Saarentaus, Finland. juha.v.virolainen@helsinki.fi
authors.forename: J V
authors.initials: JV
authors.lastname: Virolainen
authors.forename: R J
authors.initials: RJ
authors.lastname: Love
authors.forename: A
authors.initials: A
authors.lastname: Tast
authors.forename: O A T
authors.initials: OA
authors.lastname: Peltoniemi
mesh_terms: D000022:Abortion, Spontaneous / Q000139:chemically induced; D000818:Animals; D005260:Female; D007987:Gonadotropin-Releasing Hormone / Q000031:analogs & derivatives / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D007986:Luteinizing Hormone / Q000097:blood* / Q000378:metabolism; D010053:Ovary / Q000502:physiology; D011247:Pregnancy; D011270:Pregnancy, Animal / Q000097:blood / Q000187:drug effects*; D011374:Progesterone / Q000097:blood; D013552:Swine / Q000097:blood / Q000502:physiology*
chemical_list: C055689:BIM 21009; D007987:Gonadotropin-Releasing Hormone; D011374:Progesterone; D007986:Luteinizing Hormone