Wathes D C, Smith H F, Leung S T, Stevenson K R, Meier S, Jenkin G
Babraham Institute, Cambridge, UK.
J Reprod Fertil. 1996 Jan;106(1):23-31. doi: 10.1530/jrf.0.1060023.
The development of uterine oxytocin receptors is an important regulatory step in the initiation of labour. Paracrine production of oxytocin by uterine and placental tissues may also be involved in some species. Placentome, intercotyledonary endometrium, myometrium and fetal membranes were collected from 3-5 ewes each, at regular intervals throughout pregnancy and from eight ewes during labour. Localization of mRNA encoding oxytocin and its receptor was by in situ hybridization; oxytocin peptide concentrations were measured by radioimmunoassay and oxytocin receptor concentrations were measured by autoradiography and radioreceptor assay. In the intercotyledonary endometrium, mRNA encoding the oxytocin receptor was located in the luminal epithelium only. Both the epithelial and myometrial receptors were detected at low concentrations from the fourth week of gestation onwards, with a major increase associated with the onset of labour. In the placentomes, oxytocin receptors were localized to a stromal capsule surrounding the placental villi. Expression in this region was maximal in mid-gestation, declining in the second half of pregnancy and remaining low during labour. Cervical oxytocin receptors were detected at low concentrations in the epithelium and the muscular/connective tissue layers from day 22 of pregnancy onwards. There was no evidence for the local uterine production of oxytocin in the ewe; mRNA encoding oxytocin was undetectable and oxytocin concentrations were always < 23 pg g-1 wet mass of tissue. These results suggest that regulation of the timing of oxytocin receptor development varies between the different tissue types, despite a similar steroidal background. The receptors in the luminal epithelium are probably associated with the ability of exogenous oxytocin to induce the release of PGF2 alpha throughout most of pregnancy. The increase in receptors in both the intercotyledonary endometrium and myometrium at term suggest an involvement in labour, whereas their role in caruncular stroma in mid-pregnancy is unknown.
子宫催产素受体的发育是分娩启动过程中的一个重要调节步骤。在某些物种中，子宫和胎盘组织旁分泌产生催产素也可能参与其中。在整个孕期定期从3 - 5只母羊中采集胎盘、子叶间子宫内膜、子宫肌层和胎膜，分娩时从8只母羊中采集。通过原位杂交确定编码催产素及其受体的mRNA的定位；通过放射免疫测定法测量催产素肽浓度，通过放射自显影和放射受体测定法测量催产素受体浓度。在子叶间子宫内膜中，编码催产素受体的mRNA仅位于腔上皮。从妊娠第4周起，上皮和子宫肌层受体均以低浓度被检测到，随着分娩开始显著增加。在胎盘中，催产素受体定位于围绕胎盘绒毛的基质囊中。该区域的表达在妊娠中期最大，在妊娠后半期下降，分娩期间保持低水平。从妊娠第22天起，在子宫颈上皮和肌肉/结缔组织层中检测到低浓度的催产素受体。没有证据表明母羊子宫局部产生催产素；未检测到编码催产素的mRNA且催产素浓度始终<23 pg g-1湿组织质量。这些结果表明，尽管存在相似的甾体背景，但催产素受体发育时间的调节在不同组织类型之间存在差异。腔上皮中的受体可能与外源性催产素在整个孕期大部分时间诱导释放前列腺素F2α的能力有关。足月时子叶间子宫内膜和子宫肌层中受体的增加表明其参与分娩，而它们在妊娠中期肉阜基质中的作用尚不清楚。
