Relationship between endometrial oxytocin receptors and oxytocin-induced prostaglandin F2  release during the oestrous cycle and early pregnancy in pony mares

Sharp, Daniel C.; Thatcher, M.-J.; Salute, M E; Fuchs, A R

doi:10.1530/jrf.0.1090137

Cited by 74 publications

(71 citation statements)

References 20 publications

(23 reference statements)

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“…The results described here should advance our understanding of the physiology in the endometrium of the mare during these important reproductive periods. Combined with recent characterisation of the pattern of other reproductive hormones, such as oxytocin (Bae & Watson 2003) and prostaglandin F 2a (Sharp et al 1997, Handler et al 2003, results presented here provide a better understanding of endometrial physiology during the oestrous cycle and early pregnancy in the mare.…”

Section: Discussionmentioning

confidence: 68%

Temporal and spatial associations of oestrogen receptor alpha and progesterone receptor in the endometrium of cyclic and early pregnant mares

Hartt¹,

Carling²,

Joyce³

et al. 2005

Reproduction

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Uterine function is primarily controlled by the combined actions of oestrogen and progesterone working through their cognate nuclear receptors. The mechanism of establishment of pregnancy in the mare is of interest because it involves prolonged pre-attachment and conceptus migration phases, and both invasive and non-invasive placental cell types, and as such has been an important comparative model. This study characterised regulation of oestrogen (ER) and progesterone (PR) receptors in the endometrium of the mare during the oestrous cycle and early pregnancy. Endometrial tissues collected during the oestrous cycle and early pregnancy were analysed for steady-state levels of ER and PR mRNA and protein. Steady-state levels of ER and PR mRNA were highest on days 0, 17 and 20 in cyclic mares and lowest on days 11 and 14. A day-by-status interaction was detected, indicating that day 17 and day 20 pregnant mares exhibited low levels of ER and PR compared with the corresponding days of the oestrous cycle. In situ hybridisation analyses showed receptor mRNA localisation primarily in the luminal epithelium (LE), glandular epithelium (GE) and stroma around oestrus. During dioestrus and early pregnancy, receptors were not detected in the LE, and were lower in the stroma and deeper GE. Changes in hybridisation intensity in these cell types were consistent with changes in mRNA levels detected by slot-blot hybridisation. ER and PR proteins were detected in the nuclei of LE, GE and stromal cells. Consistent with results from in situ hybridisation, levels of ER and PR immunoreactivity were higher around oestrus, declined to low levels during dioestrus and remained low during early pregnancy. Results described here for temporal and spatial changes in steroid receptor gene expression in mares show the greatest similarities with those described for cattle and sheep.

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Section: Discussionmentioning

confidence: 68%

Temporal and spatial associations of oestrogen receptor alpha and progesterone receptor in the endometrium of cyclic and early pregnant mares

Hartt¹,

Carling²,

Joyce³

et al. 2005

Reproduction

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“…In studies by Tetzke et al [19], it was clearly demonstrated that the myometrium receptivity for oxytocin depends on the cycle stage. Further studies by Stull and Evans [20] and Sharp et al [21] have demonstrated that the oxytocin receptors are present to a greater extent in the myometrium than in the endometrium of non-pregnant and pregnant mares. Receptor numbers have also been shown to differ within the oestrous cycle itself as the highest concentration of receptors can be found during early oestrus (day 14 to 17), compared to late oestrus (day 18 to 0), and dioestrus (day 1 to 13) [21].…”

Section: Discussionmentioning

confidence: 96%

“…Further studies by Stull and Evans [20] and Sharp et al [21] have demonstrated that the oxytocin receptors are present to a greater extent in the myometrium than in the endometrium of non-pregnant and pregnant mares. Receptor numbers have also been shown to differ within the oestrous cycle itself as the highest concentration of receptors can be found during early oestrus (day 14 to 17), compared to late oestrus (day 18 to 0), and dioestrus (day 1 to 13) [21]. The oestrous tissue used in this study had been collected from mares in advanced oestrus (day 18 to 0) during which the receptor number has found to be lower than in early oestrus, increasing the EC 50 to some degree.…”

Section: Discussionmentioning

confidence: 96%

“…The high EC 50 of oestrous tissue suggests that an increased amount of oxytocin is needed in order to cause a response of the myometrium. Expected was that , due to a high concentration of oxytocin receptors within the myometrium during oestrus, a decreased amount of oxytocin is needed to result in a myometrial response, as suggested by literature [21].…”

Section: Discussionmentioning

confidence: 97%

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Ex vivo influence of carbetocin on equine myometrial muscles and comparison with oxytocin

et al. 2012

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In order to determine the inter-cyclic effect of oxytocin and carbetocin on equine myometrial tissue, the effect of the drugs was evaluated through pharmacokinetic and pharmaco-dynamic studies. The complete pharmacokinetic profile for oxytocin was unknown and had to be established. To do so, 25 IU of oxytocin were administered intravenously to six cycling mares and blood samples were collected before and 2, 4, 8, 2 and 15 min after administration. The half-life of oxytocin was determined to be 5.89 min, the clearance rate 11.67 l/min, MRT 7.78 min, T max 2 min, and C max 0.51 ng/ml. The effective plasma concentration was estimated to be 0.25 ng/ml. This was similar to the concentration achieved for the organ bath study where the EC 50 was calculated at 0.45 ng/ml. To determine the inter-cyclic effect of oxytocin and carbetocin uterine myometrial samples were collected from slaughtered mares in oestrus, dioestrus and anoestrus. The samples were mounted in organ baths and exposed to four ascending, cumulative doses of oxytocin and carbetocin. Area under the curve and amplitude, E max and EC 50 were studied for each agonist and statistically evaluated. The effect of oxytocin on equine myometrial tissue was higher during dioestrus, and surprisingly anoestrus, than during oestrus, whereas the effect of carbetocin was the same independent of the stage of oestrous cycle. A significant difference was found for oestrous and anoestrous samples when oxytocin was used but not when carbetocin was used.

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“…Por outro lado, o embrião eqüino não secreta IFN τ como os ruminantes (SHARP et al, 1989;BAKER et al, 1991), os receptores endometriais de ocitocina não diminuem , nem mesmo há estímulo de liberação de PGF 2α com a administração exógena de ocitocina durante gestação inicial (GOFF et al, 1987;SHARP et al, 1997 …”

Section: Composição Biossíntese E Metabolização Das Prostaglandinas unclassified

Perfil do RNAm da proteína transportadora de prostaglandina (PGT) no endométrio equino in vivo e sobre influência embrionária in vitro

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Relationship between endometrial oxytocin receptors and oxytocin-induced prostaglandin F2 release during the oestrous cycle and early pregnancy in pony mares

Cited by 74 publications

References 20 publications

Temporal and spatial associations of oestrogen receptor alpha and progesterone receptor in the endometrium of cyclic and early pregnant mares

Temporal and spatial associations of oestrogen receptor alpha and progesterone receptor in the endometrium of cyclic and early pregnant mares

Ex vivo influence of carbetocin on equine myometrial muscles and comparison with oxytocin

Perfil do RNAm da proteína transportadora de prostaglandina (PGT) no endométrio equino in vivo e sobre influência embrionária in vitro

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