title: Stimulation of LH, FSH, and luteal blood flow by GnRH during the luteal phase in mares.
abstract: A study was performed on the effect of a single dose per mare of 0 (n = 9), 100 (n = 8), or 300 (n = 9) of GnRH on Day 10 (Day 0 = ovulation) on concentrations of LH, FSH, and progesterone (P4) and blood flow to the CL ovary. Hormone concentration and blood flow measurements were performed at hours 0 (hour of treatment), 0.25, 0.5, 1, 2, 3, 4, and 6. Blood flow was assessed by spectral Doppler ultrasonography for resistance to blood flow in an ovarian artery before entry into the CL ovary. The percentage of the CL with color Doppler signals of blood flow was estimated from videotapes of real-time color Doppler imaging by an operator who was unaware of mare identity, hour, or treatment dose. Concentrations of LH and FSH increased (P < 0.05) at hour 0.25 and decreased (P < 0.05) over hours 1 to 6; P4 concentration was not altered by treatment. Blood flow resistance decreased between hours 0 and 1, but the decrease was greater (P < 0.05) for the 100-μg dose than for the 300-μg dose. The percentage of CL with blood flow signals increased (P < 0.05) between hours 0 and 1 with no significant difference between the 100- and 300-μg doses. The results supported the hypothesis that GnRH increases LH concentration, vascular perfusion of the CL ovary, and CL blood flow during the luteal phase; however, P4 concentration was not affected.
authors.affiliation: Eutheria Foundation, Cross Plains, Wisconsin, USA; Centro de Ciências Agrárias, Universidade Federal do Espírito Santo, Alegre, Espírito Santo, Brazil; Department of Pathobiological Sciences, School of Veterinary Medicine, University of Wisconsin-Madison, Madison, Wisconsin, USA.
authors.forename: T
authors.initials: T
authors.lastname: Castro
authors.affiliation: Centro de Ciências Agrárias, Universidade Federal do Espírito Santo, Alegre, Espírito Santo, Brazil.
authors.forename: F A
authors.initials: FA
authors.lastname: Oliveira
authors.affiliation: Eutheria Foundation, Cross Plains, Wisconsin, USA; Department of Pathobiological Sciences, School of Veterinary Medicine, University of Wisconsin-Madison, Madison, Wisconsin, USA.
authors.forename: M A R
authors.initials: MA
authors.lastname: Siddiqui
authors.affiliation: Eutheria Foundation, Cross Plains, Wisconsin, USA; Department of Pathobiological Sciences, School of Veterinary Medicine, University of Wisconsin-Madison, Madison, Wisconsin, USA.
authors.forename: J M
authors.initials: JM
authors.lastname: Baldrighi
authors.affiliation: Eutheria Foundation, Cross Plains, Wisconsin, USA; Department of Pathobiological Sciences, School of Veterinary Medicine, University of Wisconsin-Madison, Madison, Wisconsin, USA.
authors.forename: C A
authors.initials: CA
authors.lastname: Wolf
authors.affiliation: Eutheria Foundation, Cross Plains, Wisconsin, USA; Department of Pathobiological Sciences, School of Veterinary Medicine, University of Wisconsin-Madison, Madison, Wisconsin, USA. Electronic address: ginther@vetmed.wisc.edu.
authors.forename: O J
authors.initials: OJ
authors.lastname: Ginther
mesh_terms: D000818:Animals; D003338:Corpus Luteum / Q000098:blood supply* / Q000187:drug effects; D005260:Female; D005640:Follicle Stimulating Hormone / Q000378:metabolism*; D007987:Gonadotropin-Releasing Hormone / Q000008:administration & dosage / Q000494:pharmacology*; D006736:Horses / Q000502:physiology*; D008183:Luteal Phase / Q000187:drug effects / Q000502:physiology*; D007986:Luteinizing Hormone / Q000378:metabolism*
chemical_list: D007987:Gonadotropin-Releasing Hormone; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone
keywords: FSH; GnRH; LH; Luteal blood flow; Mare; Progesterone