Physiologic and nonphysiologic effects of exogenous prostaglandin F2α on reproductive hormones in mares

Ginther, O.J.; Siddiqui, M.A.R.; Beg, M.A.

doi:10.1016/j.theriogenology.2009.03.014

Cited by 34 publications

(26 citation statements)

References 36 publications

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“…An incorrect assumption that the responses are physiologic could lead to dubious experimental interpretations regarding the mechanism of spontaneous luteolysis. In this regard in mares, progesterone, FSH and LH increased immediately after a bolus luteolytic dose of PGF (Ginther et al 2007a(Ginther et al , 2009c, but not during the simulation of a PGFM pulse (Ginther et al 2009c). …”

Section: Introductionmentioning

confidence: 86%

“…A dose of PGF or a PGF analogue that induces complete luteolysis with a single treatment causes an immediate transient increase in progesterone prior to the decrease (Lamond et al 1973, Hixon & Hansel 1974, Skarzynski et al 2003. The transient increase is reportedly a non-physiologic response to a pharmacologic dose of PGF in heifers (Ginther et al 2009a, Shrestha et al 2010 and mares (Ginther et al 2007a(Ginther et al , 2009c. In a study with a limited number of heifers per group, an initial transient increase in progesterone occurred 10 min after a single bolus i.u.…”

Section: Introductionmentioning

confidence: 99%

“…Three hypotheses were tested in heifers in the present experiment: 1) a transient increase in progesterone occurs during infusion of PGF to simulate a natural PGFM pulse, which is based on a reported increase that did not reach significance but with a limited number of heifers (Shrestha et al 2010); 2) the luteal blood flow increase after a single luteolytic dose of PGF accompanies the progesterone decrease, which is based on a rationale from Acosta et al (2002) and 3) the immediate response of circulating hormones, other than progesterone, to a single completely luteolytic dose of PGF does not occur during a simulated pulse of PGFM, which is based on a rationale primarily from a study in mares (Ginther et al 2009c). In addition, we determined the temporal relationships between changes in progesterone concentrations and changes in luteal blood flow during and until 4 h after a 2-h simulated PGFM pulse.…”

Section: Introductionmentioning

confidence: 99%

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Luteal blood flow and concentrations of circulating progesterone and other hormones associated with a simulated pulse of 13,14-dihydro-15-keto-prostaglandin F2α in heifers

Shrestha¹,

Beg²,

Imam³

et al. 2010

Reproduction

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Progesterone and luteal blood flow effects of an i.u. 2-h infusion of 0.25 mg/h of prostaglandin F 2a (PGF) that simulated a natural pulse of 13,14-dihydro-15-keto-PGF (PGFM) were compared to the effects of a single bolus i.u. injection of PGF (4 mg) that induced complete luteolysis in heifers. Blood sampling and an estimate of the percentage of luteal area with colour-Doppler signals of blood flow were performed every 2 min for 20 min and less frequently thereafter for 6 h. After the beginning of PGF infusion or a bolus injection, progesterone increased to a peak at 14 and 10 min respectively, and was accompanied by an increase in blood flow in the bolus group but not in the infusion group. Progesterone then decreased for 1 or 2 h and was accompanied by a continued elevation in blood flow in the PGF bolus group and by a slight increase in the PGF infusion group. Progesterone then rebounded in both groups, but the rebound was greater in the infusion group. Blood flow decreased during the descending arm of the progesterone rebound. Cortisol and prolactin began to increase 6 min after the bolus PGF injection but did not increase during or after PGF infusion. The increases in cortisol, prolactin and blood flow after a PGF bolus treatment but not during a simulated PGFM pulse indicated that the bolus treatment was pharmacologic, and its use may lead to faulty conclusions on the nature of physiologic luteolysis. The comparisons between progesterone and blood flow are novel.

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Section: Introductionmentioning

confidence: 86%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Luteal blood flow and concentrations of circulating progesterone and other hormones associated with a simulated pulse of 13,14-dihydro-15-keto-prostaglandin F2α in heifers

Shrestha¹,

Beg²,

Imam³

et al. 2010

Reproduction

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“…Although the protocol chosen for systemic administration of prostaglandins appeared to be bearable for the mares, it did not have a positive effect upon follicle rupture and ovulation. A similar approach, but designed to induce full luteolysis, achieved a positive luteolytic result following intravenous administration of a low dose of PGF2a (0.1 mg) diluted in saline and infused at a constant rate over a period of 2 h (Ginther et al 2009b). Needless to say, perfusion of the CL and the follicle and the resultant arrival of prostaglandin at its target receptors within the ovary may be completely different in these two ovarian structures.…”

Section: Introductionmentioning

confidence: 99%

The role of PGE2 and PGF2a in follicle wall rupture and their implications in the development and treatment of luteinized unruptured follicles

Cuervo‐Arango¹,

Martínez-Boví²

2016

PHK

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Summary:The article summarizes the results of several studies, which highlight the relevance of prostaglandins E2 (PGE2) and F2 (PGF2a) during the ovulatory process in mares and their implication in the pathogenesis of luteinized unruptured follicles. Following the preovulatory luteinizing hormone (LH) surge, the two prostaglandins are synthesized in granulosa cells. They subsequently trigger a cascade of events that lead to ovulation. The exogenous administration of intrafollicular PGE2 and PGF2a can induce follicle rupture and ovulation within 12 h of injection, even in mares in early estrus, and before the beginning of the abrupt rise of the preovulatory LH surge. The systemic administration of a prostaglandin synthesis inhibitor (flunixin-meglumine) during the periovulatory period blocks ovulation and induces the development of luteinized unruptured follicles (LUFs). LUFs share similar ultrasonographic and hormonal characteristics with hemorragic anovulatory follicles (HAFs). The administration of intrafollicular PGE2 and PGF2a in mares treated with a prostaglandin synthesis inhibitor restores normal ovulation and allows oocyte release and fertilization. However, the systemic administration of prostaglandins does not appear to have any effect on hastening ovulation.

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“…When P4 has decreased to about half of its concentration during luteolysis, the rebound wanes. A P4 rebound after a pulse of PGFM has not been detected in mares [2,3]. Nevertheless, the primary equine CL of pregnancy undergoes well-documented natural resurgence in form and function beginning on about day 35 (day 0 ¼ ovulation) [4,5].…”

Section: Introductionmentioning

confidence: 99%

Natural Rescue and Resurgence of the Equine Corpus Luteum

Ginther

Santos

2015

Journal of Equine Veterinary Science

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Physiologic and nonphysiologic effects of exogenous prostaglandin F2α on reproductive hormones in mares

Cited by 34 publications

References 36 publications

Luteal blood flow and concentrations of circulating progesterone and other hormones associated with a simulated pulse of 13,14-dihydro-15-keto-prostaglandin F2α in heifers

Luteal blood flow and concentrations of circulating progesterone and other hormones associated with a simulated pulse of 13,14-dihydro-15-keto-prostaglandin F2α in heifers

The role of PGE2 and PGF2a in follicle wall rupture and their implications in the development and treatment of luteinized unruptured follicles

Natural Rescue and Resurgence of the Equine Corpus Luteum

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