Parkinson T J, Jenner L J, Lamming G E
AFRC Research Group on Hormones and Farm Animal Reproduction, University of Nottingham, School of Agriculture, Loughborough, Leics, UK.
J Reprod Fertil. 1990 Sep;90(1):337-45. doi: 10.1530/jrf.0.0900337.
The secretion of prostaglandin (PG) F-2 alpha in response to intravenous injection of 100 i.u. oxytocin on Day 18 after oestrus was determined by measuring jugular venous concentrations of 13,14-dihydro-15-keto PGF-2 alpha (PGFM) in 7 pregnant, 6 cyclic and 2 inseminated non-pregnant heifers. Two other heifers received i.v. saline (controls). The immediate responses of pregnant heifers were smaller than in non-pregnant animals (P less than 0.05), as were baseline concentrations in the post-response period (P less than 0.05). Endometrial oxytocin receptor concentrations were higher in nonpregnant than pregnant heifers (P less than 0.05), but PGFM response to oxytocin challenge was not correlated with oxytocin receptor concentration. Oxytocin receptor concentrations on Day 18 were positively correlated with those of plasma oestradiol on Day 17 (P less than 0.01) and inversely with plasma progesterone concentrations on Day 18 (P less than 0.01). These findings confirm that PGF-2 alpha secretion in response to oxytocin challenge is attenuated in pregnant animals on the 18th day after oestrus and that, while the prevailing steroid environment is of importance in inducing oxytocin receptor activity, the secretion of PGF-2 alpha is not subsequently limited by oxytocin receptor numbers. The quantities of PGE-2, PGFM and PGF-2 alpha recovered in uterine flushings taken from heifers on Day 18 were greater in pregnant than other animals (P less than 0.01, P less than 0.05, P less than 0.001, respectively). Intrauterine concentrations of PGF-2 alpha and PGFM were not correlated with the plasma PGFM responses.
通过测量7头怀孕、6头发情周期正常以及2头人工授精未怀孕的小母牛颈静脉中13,14 - 二氢 - 15 - 酮PGF - 2α（PGFM）的浓度，来测定发情后第18天静脉注射100国际单位催产素后前列腺素（PG）F - 2α的分泌情况。另外2头小母牛静脉注射生理盐水作为对照。怀孕小母牛的即时反应比未怀孕动物小（P < 0.05），反应后阶段的基线浓度也是如此（P < 0.05）。未怀孕小母牛子宫内膜催产素受体浓度高于怀孕小母牛（P < 0.05），但PGFM对催产素刺激的反应与催产素受体浓度无关。第18天的催产素受体浓度与第17天的血浆雌二醇浓度呈正相关（P < 0.01），与第18天的血浆孕酮浓度呈负相关（P < 0.01）。这些发现证实，发情后第18天，怀孕动物对催产素刺激的PGF - 2α分泌减弱，虽然主要的类固醇环境对诱导催产素受体活性很重要，但PGF - 2α的分泌随后并不受催产素受体数量的限制。从第18天的小母牛子宫冲洗液中回收的PGE - 2、PGFM和PGF - 2α的量，怀孕小母牛比其他动物多（分别为P < 0.01、P < 0.05、P < 0.001）。子宫内PGF - 2α和PGFM的浓度与血浆PGFM反应无关。
