Equine Embryonic, Luteal and Endometrial Interactions in Pregnancy Recognition

母马的黄体、子宫和胚胎组织参与母体妊娠识别（MRP），但其发生的详细机制仍未得到解决。马的早孕失败是造成经济损失的原因，影响了超过10%的马怀孕。马的高妊娠率是妊娠识别研究的一个令人信服的原因。了解母马妊娠识别（MRP）的相关因素及其调控，是预防早期妊娠丢失的必要条件。我们的研究集中在检查催产素（Oxy）的作用，以及代谢Oxy的酶，即催产素酶（OTase）在马MRP中的作用。我们报道了oase存在于未怀孕和怀孕母马的血清中。我们确定oase水平不受黄体酮（P4）的调节，因为随着P4水平的下降，oase水平不会发生变化。组织中有高水平的OTase （U/g组织），免疫组化显示OTase存在于子宫内膜上皮；子宫肌层;还有胎盘组织。催产素在产妇行为、泌乳、子宫收缩和胎盘分娩中起着核心作用。全身的氧水平受到包括oase在内的快速清除机制的严格调节。我们将研究OTNP-1向Oxy的转化，进一步明确Oxy在MRP中的作用。众所周知，催产素通过其受体起作用，可以增加其他组织中前列腺素（PG）的分泌。MRP需要排卵后5-15天的胚胎活动能力。催产素、oase和PG可能参与胚胎的运动。我们将比较用已知影响胚胎流动性的不同PG抑制剂治疗的怀孕母马。我们将应用：子宫内膜，胚胎和黄体组织的分子研究；超声成像工具；还有激素检测。我们将在排卵后第10天对未怀孕的母马进行研究，用子宫内脉冲治疗：生理盐水、雌激素、氧、PGF、PGE、PGE和PGF来模拟自然。阻断或改变PG脉冲或PGE - PGE比值被认为会影响黄体功能，而黄体功能是MRP的关键。治疗对P4、黄体组织、激素、基因表达和蛋白质的影响将被确定。我们还将通过体外培养排卵后不同天的黄体和子宫内膜细胞来识别MRP调节信号。细胞将用条件培养基、激素、抑制剂和激动剂处理。治疗效果将通过基因和蛋白质的分子分析以及各种激素的分泌来检验。然后将探索可能的调节物质，以了解其潜在的分子作用机制。通过这些不同的方法，我们将能够确定影响胚胎流动性、黄体功能的调节因素以及与MRP相关的调节途径。这些信息将用于开发旨在减少母马早期妊娠损失的疗法。

Luteal, uterine and embryonic tissues are involved in the maternal recognition of pregnancy (MRP) in mares, but the detailed mechanism of how this occurs, remains unsolved. Early pregnancy failure in horses is a cause of economic loss and affects more than 10% of equine pregnancies. This high rate of equine pregnancy loss is a compelling cause for research in pregnancy recognition. An understanding of the factors involved in the maternal recognition of pregnancy (MRP) in mares, and their regulation, is required to prevent early pregnancy losses. Our research has concentrated on examining the role of oxytocin (Oxy), and the enzyme that metabolizes Oxy, called oxytocinase (OTase) in equine MRP. We reported that OTase is present in serum in non-pregnant and pregnant mares. We determined that levels of OTase are not regulated by progesterone (P4), as levels do not vary as P4 levels decline. There are high levels of OTase (U/g tissue) in tissues, and immunohistochemistry reveals that OTase is present in endometrial epithelium; myometrium; and placental tissue. Oxytocin has a central role in: maternal behaviour, milk ejection, uterine contraction, and placental delivery. Systemic levels of Oxy are tightly regulated by rapid clearance mechanisms involving OTase. We will study the conversion of OTNP-1 to Oxy, and further clarify the role of Oxy in MRP. Oxytocin acting through its receptor, is know to increase prostaglandin (PG) secretion in other tissues. Embryo mobility from day 5-15 post-ovulation is required for MRP. Oxytocin, OTase and PG are likely involved in embryo mobility. We will compare pregnant mares that are treated with different PG inhibitors known to effect embryo mobility. We will apply: molecular studies of endometrial, embryonic and luteal tissues; ultrasound imaging tools; and hormone assays. We will study non-pregnant mares on day 10 after ovulation, treated with intrauterine pulses of: saline, estrogen, Oxy, PGF, PGE, and PGE and PGF to mimic nature. Intercepting or changing the pulses of PG, or the PGE PGE ratio, is thought to affect luteal function, which is key for MRP. The effects of treatment on P4, luteal tissue, hormones, gene expression and proteins will be determined. We will also identify MRP regulatory signals by using in vitro cultures of luteal and endometrial cells from different days post-ovulation. Cells will be treated with conceptus conditioned media, hormones, inhibitors and agonists. Treatment effects will be examined using molecular analyses of genes and proteins, and secretion of various hormones. Possible regulatory substances will then be explored for their underlying molecular mechanism of action. We will, through these diverse approaches, be able to identify regulatory factors that influence embryo mobility, luteal function and the regulatory pathways associated with MRP. This information will be applied to develop therapies aimed at decreasing early pregnancy loss in mares.