Hartt L S, Carling S J, Joyce M M, Johnson G A, Vanderwall D K, Ott T L
Department of Animal and Veterinary Science, Center for Reproductive Biology, University of Idaho, Moscow, Idaho 83844-2330, USA.
Reproduction. 2005 Aug;130(2):241-50. doi: 10.1530/rep.1.00596.
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.
子宫功能主要受雌激素和孕激素通过其同源核受体共同作用的调控。母马妊娠建立的机制备受关注，因为它涉及较长的着床前和胚胎迁移阶段，以及侵袭性和非侵袭性胎盘细胞类型，因此一直是一个重要的比较模型。本研究对母马发情周期和妊娠早期子宫内膜中雌激素（ER）和孕激素（PR）受体的调控进行了表征。分析了发情周期和妊娠早期收集的子宫内膜组织中ER和PR mRNA及蛋白的稳态水平。在发情周期的母马中，ER和PR mRNA的稳态水平在第0、17和20天最高，在第11和14天最低。检测到日状态交互作用，表明与发情周期的相应天数相比，妊娠第17天和第20天的母马ER和PR水平较低。原位杂交分析显示，受体mRNA主要定位在发情期周围的腔上皮（LE）、腺上皮（GE）和基质中。在间情期和妊娠早期，LE中未检测到受体，基质和深层GE中的受体水平较低。这些细胞类型中杂交强度的变化与狭缝印迹杂交检测到的mRNA水平变化一致。在LE、GE和基质细胞的细胞核中检测到ER和PR蛋白。与原位杂交结果一致，ER和PR免疫反应性水平在发情期周围较高，在间情期下降至低水平，并在妊娠早期保持低水平。这里描述的母马类固醇受体基因表达的时空变化结果与牛和羊的结果最为相似。
