Sheldrick E L, Flint A P
Prostaglandins. 1981 Oct;22(4):631-6. doi: 10.1016/0090-6980(81)90072-1.
Plasma concentrations of oxytocin and progesterone have been measured by radioimmunoassay in jugular venous blood obtained daily from 5 sheep during 2 estrous cycles and in early pregnancy. Concentrations of oxytocin were relatively high (15-30) pg/ml) during the luteal phase of the cycle, but fell at estrus (to 1-17 pg/ml). A fall in oxytocin was also observed on day 15 of pregnancy, when, as expected, progesterone levels remained high. It is suggested that raised basal levels of oxytocin are unlikely to cause the increased uterine release of prostaglandin F2 alpha which occurs at the end of the estrous cycle.
在两个发情周期以及妊娠早期，每天从5只绵羊采集颈静脉血，通过放射免疫分析法测定其中催产素和孕酮的血浆浓度。在发情周期的黄体期，催产素浓度相对较高（15 - 30皮克/毫升），但在发情期下降（至1 - 17皮克/毫升）。在妊娠第15天也观察到催产素下降，此时孕酮水平如预期保持在高位。研究表明，基础催产素水平升高不太可能导致发情周期末期子宫前列腺素F2α释放增加。
