Robinson R S, Mann G E, Lamming G E, Wathes D C
Department of Veterinary Basic Sciences, Royal Veterinary College, Hawkshead Road, Potters Bar, Hertfordshire EN6 1NB, UK.
J Endocrinol. 1999 Jan;160(1):21-33. doi: 10.1677/joe.0.1600021.
The expression of oxytocin receptor (OTR) in the uterine endometrium plays an important role in the initiation of luteolysis. During early pregnancy, the conceptus secretes interferon tau (IFN|gt) which inhibits OTR up-regulation and luteolysis. In this study, uterine horn cross sections were collected on day 16 from 15 pregnant cows (PREG), 9 uninseminated controls and 5 inseminated cows with no embryo present. The latter two groups had similar results and were combined to form a single non-pregnant (NP) group. The animals were given an oxytocin challenge shortly before tissue collection to assess prostaglandin F2alpha (PGF2alpha) release through the measurement of the metabolite 13,14-dihydro-15-keto PGF2alpha (PGFM). The mRNAs for OTR, oestrogen receptor (ER) and progesterone receptor (PR) were localised by in situ hybridisation. The results were quantified by optical density (OD) measurements from autoradiographs using image analysis. OTR protein was measured by autoradiography with iodinated oxytocin antagonist and ER and PR protein was detected by immunocytochemistry. The release of PGFM after the oxytocin challenge was significantly higher in the 14 NP cows (187%+/-15%) compared with the PREG group (131%+/-11%) (P<0.01). Low concentrations of OTR mRNA were localised to the luminal epithelium (LE) in 6 out of the 14 NP cows, of which 2 also expressed OTR protein, while OTR mRNA and protein were undetectable in all the pregnant animals. These results indicated that the sampling time coincided with the onset of the luteolytic mechanism in the NP cows. On day 16 ER mRNA was detectable in both the LE and glands of both PREG and NP animals. There were no differences in either ER mRNA or protein between NP and PREG samples. PR mRNA was moderately expressed in the caruncular stroma, with lower levels in the dense caruncular-like stroma and glands. There were no differences between PREG and NP animals. The expression of PR mRNA and protein in the deep glands was variable between animals. These results suggested that, in cows, the presence of an embryo suppressed the expression of OTR, but had no effect on the expression of the transcriptionally regulated ER on day 16.
催产素受体（OTR）在子宫内膜中的表达在黄体溶解起始过程中起重要作用。在妊娠早期，胚胎分泌干扰素τ（IFNτ），其抑制OTR上调和黄体溶解。在本研究中，于第16天从15头妊娠母牛（PREG）、9头未授精对照母牛以及5头授精但无胚胎的母牛采集子宫角横断面。后两组结果相似，合并形成单个非妊娠（NP）组。在组织采集前不久对动物进行催产素激发试验，通过测量代谢物13,14 - 二氢 - 15 - 酮PGF2α（PGFM）来评估前列腺素F2α（PGF2α）释放。通过原位杂交定位OTR、雌激素受体（ER）和孕激素受体（PR）的mRNA。使用图像分析通过对放射自显影片的光密度（OD）测量对结果进行定量。用碘化催产素拮抗剂通过放射自显影法测量OTR蛋白，并用免疫细胞化学法检测ER和PR蛋白。催产素激发试验后，14头NP母牛的PGFM释放量（187%±15%）显著高于PREG组（131%±11%）（P<0.01）。14头NP母牛中有6头的OTR mRNA低水平定位于腔上皮（LE），其中2头也表达OTR蛋白，而在所有妊娠动物中均未检测到OTR mRNA和蛋白。这些结果表明采样时间与NP母牛黄体溶解机制的起始时间一致。在第16天，PREG和NP动物的LE和腺体中均可检测到ER mRNA。NP和PREG样本之间的ER mRNA或蛋白均无差异。PR mRNA在肉阜基质中中度表达，在致密的类肉阜基质和腺体中表达水平较低。PREG和NP动物之间无差异。动物之间深腺体中PR mRNA和蛋白的表达存在差异。这些结果表明，在母牛中，胚胎的存在抑制了OTR的表达，但在第16天对转录调控的ER的表达没有影响。
