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Domingues RR, Ginther OJ, Gomez-Leon V, Castro T, Wiltbank MC. Endometrial and luteal responses to a prostaglandin F2alpha pulse: A comparison between heifers and mares. Biol Reprod 2022; 106:979-991. [DOI: 10.1093/biolre/ioac025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Revised: 12/28/2021] [Accepted: 01/25/2022] [Indexed: 11/13/2022] Open
Abstract
Abstract
In heifers and mares, multiple pulses of prostaglandin F2alpha (PGF) are generally associated with complete luteal regression. Although PGF pulses occur before and during luteolysis, little is known about the role of minor PGF pulses during preluteolysis on subsequent luteal and endometrial PGF production that may initiate luteolysis. Heifers (n = 7/group) and mares (n = 6/group) were treated with a single minor dose of PGF (3.0 and 0.5 mg, respectively) during mid-luteal phase (12 and 10 days postovulation in heifers and mares, respectively). After treatment, a transient decrease in progesterone (P4) concentrations occurred in heifers between Hours 0–2 but at Hour 4 P4 was not different from pre-treatment. In mares, P4 was unaltered between Hours 0 and 4. Concentrations of P4 decreased in both species by Hour 24 and complete luteolysis occurred in mares by Hour 48. Luteal and endometrial gene expression were evaluated 4 hours post-treatment. In heifers, luteal mRNA abundance of PGF receptor and PGF dehydrogenase were decreased while PTGS2, PGF transporter, and oxytocin receptor were increased. In the heifer endometrium, receptors for oxytocin, P4, and estradiol were upregulated. In mares, luteal expression of PGF receptor was decreased while PGF transporter and oxytocin receptor were increased. The decrease in P4 between Hours 4 and 24 and changes in gene expression were consistent with upregulation of endogenous synthesis of PGF. The hypotheses were supported that a single minor PGF treatment upregulates endogenous machinery for PGF synthesis in heifers and mares stimulating endogenous PGF synthesis through distinct regulatory mechanisms in heifers and mares.
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Affiliation(s)
- Rafael R Domingues
- Department of Animal and Dairy Sciences, University of Wisconsin-Madison, Madison, WI, USA
- Endocrinology and Reproductive Physiology Program, University of Wisconsin-Madison, Madison, WI, USA
- Eutheria Foundation, Cross Plains, WI, USA
| | - O J Ginther
- Eutheria Foundation, Cross Plains, WI, USA
- Department of Pathobiological Sciences, School of Veterinary Medicine, University of Wisconsin-Madison, Madison, WI, USA
| | - Victor Gomez-Leon
- Department of Animal and Dairy Sciences, University of Wisconsin-Madison, Madison, WI, USA
- Eutheria Foundation, Cross Plains, WI, USA
| | - Thadeu Castro
- Eutheria Foundation, Cross Plains, WI, USA
- Department of Veterinary Medicine, Universidade Federal Rural do Rio de Janeiro, Seropédica, RJ, Brazil
| | - Milo C Wiltbank
- Department of Animal and Dairy Sciences, University of Wisconsin-Madison, Madison, WI, USA
- Endocrinology and Reproductive Physiology Program, University of Wisconsin-Madison, Madison, WI, USA
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Ginther OJ, Domingues RR, Kennedy VC, Dangudubiyyam SV. Endogenous and exogenous effects of PGF2α during luteolysis in mares. Theriogenology 2019; 132:45-52. [PMID: 30991168 DOI: 10.1016/j.theriogenology.2019.04.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2019] [Revised: 04/02/2019] [Accepted: 04/04/2019] [Indexed: 12/14/2022]
Abstract
An inhibitor of PGF2α biosynthesis (flunixin meglumine, FM) was used to study the role of endogenous PGF2α on the luteolytic effect of exogenous PGF2α in mares. A 2-h infusion of PGF2α at a constant rate (total dose, 0.1 mg) on Day 10 (ovulation = Day 0) was used to mimic the maximal concentrations of a spontaneous pulse of a PGF2α metabolite (PGFM). Treatment with FM (1.7 mg/kg) was done 1 h before and 5 h after the start of PGF2α infusion. In hourly blood samples beginning 1 h before the start of PGF2α infusion, progesterone decreased (P < 0.05) similarly by 5 h in each of the PGF2α and PGF2α+FM groups but not in the controls (n = 5). In a study of spontaneous luteolysis, the same FM dose was given every 6 h from Day 13 until Day 17 or earlier if CL regression was indicated by an 80% decrease in luteal blood-flow signals. Blood was sampled for progesterone assay each day and 8 h of hourly blood sampling was done each day to characterize PGFM concentrations and pulses. Progesterone (P4) was lower (P < 0.05) in controls than in an FM group (n = 7) by Day 15. Luteolysis (P4 < 1 ng/mL) ended on Days 14-19 in individual controls. In contrast, luteolysis did not end until after Day 20 in 4 of 7 FM-treated mares. In the three mares with completion of luteolysis before Day 20 in the FM group, the interval from beginning to end of luteolysis was longer (P < 0.02) (4.5 ± 0.6 days) than in the controls (3.0 ± 0.4 days). During 8-h sessions of hourly blood sampling on Day 14, concentration of PGFM was significantly lower in the FM group for the minimal, mean, and maximal per session. Pulses of PGFM were identified by a CV methodology on each day in 7 of 7 and 3 of 7 mares in the controls and FM group, respectively. The four FM-treated mares without a CV-identified pulse were the four mares in which luteolysis did not occur before Day 20. In mares with detected pulses, PGFM was lower at each nadir and at the peak (86% lower) in the FM group than in controls, but the interval between nadirs or base of a pulse was not different between groups. Hypothesis 1 that endogenous PGF plays a role in the luteolytic effect of exogenous PGF2α was not supported. Hypothesis 2 that an inhibitor of PGF2α biosynthesis prevented or minimized the prominence of PGFM pulses and increased the frequency of persistent CL was supported.
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Affiliation(s)
- O J Ginther
- Eutheria Foundation, Cross Plains, WI, 53528, USA; Department of Pathobiological Sciences, School of Veterinary Medicine, University of Wisconsin-Madison, Madison, WI, 53706, USA.
| | - R R Domingues
- Eutheria Foundation, Cross Plains, WI, 53528, USA; Department of Pathobiological Sciences, School of Veterinary Medicine, University of Wisconsin-Madison, Madison, WI, 53706, USA
| | - V C Kennedy
- Eutheria Foundation, Cross Plains, WI, 53528, USA
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