title: Circulating nitric oxide metabolites during luteolysis and the effect of luteinizing hormone on circulating nitric oxide metabolites in heifers.
abstract: Temporal relationships among circulating concentrations of nitric oxide metabolites (NOM), progesterone (P4), and luteinizing hormone (LH) within the hours of a PGFM pulse were studied during luteolysis in heifers. The peak of a PGFM pulse was designated Hour 0. All of the following increases and decreases were significant. Within a spontaneous PGFM pulse (experiment 1; n = 7), concentrations of P4 and LH decreased between Hours -1 and 0 and increased between Hours 0 and 1; NOM increased between Hours -1 and 2. In experiment 2, PGFM pulses were simulated by intrauterine infusion of PGF2α (PGF group, n = 6), and another group was also treated with acyline to inhibit LH secretion (acyline-PGF group, n = 6). Averaged over the two groups, concentration of P4 decreased between Hours -2 and 0, increased (rebounded) between Hours 0 and 1, and decreased after Hour 2. In the PGF group, concentration of LH decreased between Hours -2 and -0.5 and increased between Hour 0 and Hour 1.5 to a maximum at Hour 1.5; NOM decreased between Hours -2 and -1.5 and increased between Hours 0 and 1.5. In the acyline-PGF group, the effect of hour was not significant for concentrations of LH and NOM. The absence of an increase in NOM concentration when LH was inhibited is a novel finding. The hypotheses were supported that concentrations of LH and NOM are temporally related, and LH has a role in the increase in NOM within the hours of a PGFM pulse.
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: Greene
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; D002417:Cattle / Q000097:blood*; D015237:Dinoprost / Q000008:administration & dosage / Q000031:analogs & derivatives / Q000097:blood; D005260:Female; D007986:Luteinizing Hormone / Q000097:blood / Q000494:pharmacology*; D003341:Luteolysis / Q000502:physiology*; D009569:Nitric Oxide / Q000097:blood*; D010507:Periodicity; D011374:Progesterone / Q000097:blood
chemical_list: C008228:15-keto-13,14-dihydroprostaglandin F2alpha; D009569:Nitric Oxide; D011374:Progesterone; D007986:Luteinizing Hormone; D015237:Dinoprost
keywords: Blood flow; Luteinizing hormone; Luteolysis; Nitric oxide; PGF2α