Carnahan K G, Prince B C, Ludwig T E, Uzumcu M, Evans M A, Mirando M A
Department of Animal Sciences, Center for Reproductive Biology, Washington State University, Pullman 99164, USA.
J Reprod Fertil. 1999 Nov;117(2):207-12. doi: 10.1530/jrf.0.1170207.
The aim of this study was to determine the effect of oxytocin on PGF2 alpha secretion into the uterine lumen of pigs and subsequent endometrial responsiveness to oxytocin in vitro. Cyclic, pregnant and oestradiol-induced pseudopregnant gilts were injected i.v. with vehicle or 20 iu oxytocin 10 min before hysterectomy on day 16 after oestrus. Concentrations of PGF2 alpha and 13,14-dihydro-15-keto PGF2 alpha (PGFM) were significantly increased in uterine flushings collected at hysterectomy (P < 0.05) in pregnant oxytocin-injected gilts. Concentrations of PGF2 alpha and PGFM were greater (P < 0.001) in pregnant than in pseudopregnant and cyclic gilts, and greater (P < 0.01) in pseudopregnant than in cyclic gilts. The ratio of PGFM:PGF2 alpha tended to be greater in cyclic (P < 0.06) and pseudopregnant gilts (P < 0.1) than in pregnant gilts. At 85 +/- 5 min after oxytocin injection, endometrium from each gilt was incubated for 3 h for determination of phosphoinositide hydrolysis and PGF2 alpha secretion in response to treatment with 0 or 100 nmol oxytocin l-1. Endometrial phosphoinositide hydrolysis in response to 100 nmol oxytocin l-1 in vitro was greater (P < 0.05) in cyclic oxytocin-injected gilts than in cyclic vehicle-injected gilts. Treatment with oxytocin in vitro did not stimulate phosphoinositide hydrolysis significantly in vehicle- or oxytocin-injected pregnant gilts or pseudopregnant gilts. Endometrial PGF2 alpha secretion increased after treatment with 100 nmol oxytocin l-1 in vitro in cyclic vehicle-injected (P < 0.01), cyclic oxytocin-injected (P < 0.01), pregnant vehicle-injected (P = 0.06), pseudopregnant vehicle-injected (P < 0.05) and pseudopregnant oxytocin-injected (P < 0.05) gilts, but not in pregnant oxytocin-injected gilts. The increase in PGF2 alpha in pseudopregnant oxytocin-injected gilts was less (P < 0.05) than that in cyclic oxytocin-injected gilts. These results indicate that oxytocin increases the concentration of PGF2 alpha and PGFM in the uterine lumen during pregnancy and may upregulate endometrial responsiveness to oxytocin during late dioestrus in pigs, but does not have the latter effect during early pregnancy or oestradiol-induced pseudopregnancy.
本研究的目的是确定催产素对猪子宫腔内前列腺素F2α（PGF2α）分泌的影响，以及随后体外子宫内膜对催产素的反应性。在发情后第16天进行子宫切除术前10分钟，对处于发情周期、怀孕和经雌二醇诱导的假孕母猪静脉注射溶媒或20国际单位催产素。在怀孕且注射催产素的母猪子宫切除时收集的子宫冲洗液中，PGF2α和13,14 - 二氢 - 15 - 酮PGF2α（PGFM）的浓度显著升高（P < 0.05）。怀孕母猪中PGF2α和PGFM的浓度高于假孕和处于发情周期的母猪（P < 0.001），假孕母猪中的浓度高于处于发情周期的母猪（P < 0.01）。PGFM与PGF2α的比值在处于发情周期（P < 0.06）和假孕的母猪中倾向于高于怀孕母猪（P < 0.1）。在注射催产素后85 ± 5分钟，将每头母猪的子宫内膜孵育3小时，以测定磷酸肌醇水解以及对0或100 nmol/L催产素处理的PGF2α分泌情况。在体外，注射催产素的处于发情周期的母猪对100 nmol/L催产素的子宫内膜磷酸肌醇水解作用大于注射溶媒的处于发情周期的母猪（P < 0.05）。在体外，对注射溶媒或催产素的怀孕母猪或假孕母猪用催产素处理并未显著刺激磷酸肌醇水解。在体外，用100 nmol/L催产素处理后，注射溶媒的处于发情周期的母猪（P < 0.01）、注射催产素的处于发情周期的母猪（P < 0.01）、注射溶媒的怀孕母猪（P = 0.06）、注射溶媒的假孕母猪（P < 0.05）和注射催产素的假孕母猪（P < 0.05）的子宫内膜PGF2α分泌增加，但注射催产素的怀孕母猪未增加。注射催产素的假孕母猪中PGF2α的增加量小于注射催产素的处于发情周期的母猪（P < 0.05）。这些结果表明，催产素可增加怀孕期间子宫腔内PGF2α和PGFM的浓度，并且可能在猪发情后期上调子宫内膜对催产素的反应性，但在怀孕早期或经雌二醇诱导的假孕期间没有这种作用。
