Diestrus administration of oxytocin prolongs luteal maintenance and reduces plasma PGFM concentrations and endometrial COX-2 expression in mares

Keith, L; Ball, Barry A.; Scoggin, Kirsten E.; Esteller-Vico, A.; Woodward, Elizabeth M.; Troedsson, Mats H.T.; Squires, E.L.

doi:10.1016/j.theriogenology.2012.11.015

Cited by 25 publications

(20 citation statements)

References 45 publications

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“…In comparison, the three highest doses in the present project were equivalent to an average of 5, 10, and 20 IU/mare. The daily injection of pharmacologically high doses of OT prevents luteolysis in association with suppression of PGF2a by a decrease in endometrial expression of cyclooxygenase 2 and not by a decrease in OT receptor expression [31] or differences in OT binding capacity of the endometrium [30].…”

Section: Discussionmentioning

confidence: 98%

“…Less effectiveness of a high dose of OT than a lower dose in stimulating a luteolytic PGFM pulse may be related to the induction of a persistent CL with chronic [28] or daily administration of OT in high doses (e.g., 60 IU/mare [29][30][31]). In comparison, the three highest doses in the present project were equivalent to an average of 5, 10, and 20 IU/mare.…”

Section: Discussionmentioning

confidence: 99%

“…In this regard, the number of OT receptors in the uterus is minimal on Days 4 to 8 in mares [27]. Despite the stimulation of PGFM by OT doses of 10 to 25 IU/mare [18,20], chronic administration of OT in high doses (e.g., 60 IU/day on Days 7-14) prolongs the luteal phase at least until Day 30 [28][29][30][31]. Furthermore, 60 IU of OT on Days 8 to 14 prolongs the luteal phase (P4 > 1.0 ng/mL until Day 30), reduces endometrial cyclooxygenase-2 expression, and lowers plasma concentrations of PGFM [31].…”

Section: Introductionmentioning

confidence: 99%

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Oxytocin induction of pulses of a prostaglandin metabolite and luteolysis in mares

et al. 2015

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Section: Discussionmentioning

confidence: 98%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Oxytocin induction of pulses of a prostaglandin metabolite and luteolysis in mares

et al. 2015

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“…In cyclic mares, this response is the highest at luteolysis (late luteal phase) and related to increased endometrial OXTR (Ruijter-Villani et al 2014). Instead, OXT administration to mares in mid luteal phase (day 8 to 14) blocks luteolysis and extends the luteal phase (Stout et al 1999, Keith et al 2013. Nevertheless, the exact mechanism involved in this action needs to be determined.…”

Section: Prostaglandin and Oxytocin In Endometriummentioning

confidence: 99%

Dual effect of hormones on mare reproductive physiology and dysfunction

Rebordão¹,

Amaral²,

Galvão³

et al. 2016

PHK

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Summary: In the last decades, classical and molecular biology approaches have greatly contributed for building up sound knowledge on the mechanisms regulating reproductive processes in the mare. Different perspectives on the role of hormones should be addressed and thus considered by both researchers and clinicians. While oxytocin is largely used as a post-insemination method to improve fertility or prevent endometritis, it may also be considered to prolong the luteal phase. Prostaglandin E2 (PGE2), known to sustain luteostasis, has also been related to inflammatory processes in sub-clinical endometritis in mares. In contrast, as other ecbolic agents, PGF2a besides being luteolytic and currently used for estrous cycle shortening and endometritis control, might also play a role in fibrogenesis in mare endometrium. Hormones, like oxytocin, ovarian steroids, prostaglandins (PG), as well as enzyme profiles involved in endocrine pathways may act in a dissimilar fashion, depending on the estrous cycle phase and on the physiologic or pathologic condition.Keywords: mare / reproduction / oxytocin / prostaglandin / endometrium / fibrosis / ovarian steroids Doppeleffekt von Hormonen auf die Reproduktionsphysiologie und -störung bei der StuteIn den letzten Jahrzehnten haben die klassischen und molekularbiologische Methoden in hohen Maße für die Entwicklung fundierten Wissens zu den Regelmechanismen reproduktiver Prozesse bei der Stute beigetragen. Es sollten die unterschiedliche Sichtweisen auf die Rolle der Hormone berücksichtigt werden, sowohl von Forschern als auch Klinikern. Während Oxytocin überwiegend als Verfahren nach der Insemination verwendet wird, um die Fruchtbarkeit zu verbessern oder eine Endometritis zu verhindern, kann es auch eingesetzt werden, um die Gelbkörperphase zu verlängern. Prostaglandin E2 (PGE2) ist bekannt, die Luteostase zu erhalten, wird aber auch mit entzündlichen Prozessen bei der equinen subklinische Endometritis in Verbindung gebracht. Im Gegensatz dazu könnte PGF2a, wie andere ekbolische Mittel, abgesehen davon, dass es luteolytisch wirkt und derzeit benutzt wird, den Ovarialzyklus zu verkürzen und eine Endometritis zu kontrollieren, auch eine Rolle bei der Fibrogenese im equinen Endometrium spielen. Hormone wie Oxytocin, Ovarialsteroide, Prostaglandine (PG), als auch Enzymprofile, die an endokrinen Regelkreisen beteiligt sind, können in einer unterschiedlichen Art und Weise wirken, abhängig von der Zyklusphase und dem physiologischen oder pathologischen Zustand.

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“…Further supporting evidence for involvement of oxytocin in regulation of luteolysis and its alteration during maternal recognition of pregnancy comes from the observation that repeated administration of oxytocin prolongs luteal function in mares (Stout et al 1999 ;Vanderwall et al 1994Vanderwall et al , 2007. Oxytocin receptor transcript levels remain unaltered in mares displaying prolonged luteal function following repeated oxytocin exposure, whereas prostaglandin-endoperoxide synthase 2 expression is reduced (Keith et al 2013 ).…”

Section: Prostaglandin F2α Release Is Attenuated During Maternal Recomentioning

confidence: 98%

Pregnancy Recognition and Implantation of the Conceptus in the Mare

Klein

2015

Regulation of Implantation and Establishment of Pregnancy in Mammals

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Few, if any, biological processes are as diverse among domestic species as establishment of early pregnancy, in particular maternal recognition of pregnancy. Following fertilization and initial development in the mare oviduct, selective transport of the embryo through the uterotubal junction driven by embryo-derived PGE2 occurs. Upon arrival in the uterus, an acellular glycoprotein capsule is formed that covers the embryo, blastocyst, and conceptus (embryo and associated extraembryonic membranes) between the second and third weeks of pregnancy. Between Days 9 and 15/16 of pregnancy, the conceptus undergoes an extended phase of mobility. Conceptus mobility is driven by conceptus-derived PGF2α and PGE2 that stimulate uterine contractions which in turn propel migration of the conceptus within the uterine lumen. Cessation of conceptus mobility is referred to as fixation and appears to be attributable to increasing size of the conceptus, preferential thickening of the endometrium near the mesometrial attachment referred to as encroachment, and a reduction in sialic acid content of the capsule. During maternal recognition of pregnancy, endometrial PGF2α release is attenuated, a consequence of reduced expression of key enzymes involved in prostaglandin production. Oxytocin responsiveness is altered during early pregnancy, and reduced expression of the oxytocin receptor appears to be regulated at the posttranscriptional level rather than the transcriptional level. Prostaglandin release is attenuated temporarily only during early pregnancy; during the third week of pregnancy, the endometrium resumes the ability to secrete PGF2α. The equine conceptus initiates steroidogenesis as early as Day 6 and synthesizes estrogens, androgens, and progesterone. Estrogens are metabolized locally, presumably regulating their bioavailability and actions. Results of experiments attempting to prove that conceptus-derived estrogens are responsible for extension of corpus luteum function have been inconclusive. By the fourth week of pregnancy, the chorionic girdle becomes visible on the trophoblast. Subsequent invasion of chorionic girdle cells leads to formation of endometrial cups which secrete equine chorionic gonadotropin. Equine chorionic gonadotropin has luteinizing hormone functions in the mare, causing luteinization of follicles resulting in the formation of secondary corpora lutea essential to production of progesterone and maintenance of pregnancy.

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Diestrus administration of oxytocin prolongs luteal maintenance and reduces plasma PGFM concentrations and endometrial COX-2 expression in mares

Cited by 25 publications

References 45 publications

Oxytocin induction of pulses of a prostaglandin metabolite and luteolysis in mares

Oxytocin induction of pulses of a prostaglandin metabolite and luteolysis in mares

Dual effect of hormones on mare reproductive physiology and dysfunction

Pregnancy Recognition and Implantation of the Conceptus in the Mare

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