Franczak A, Kotwica G
Department of Animal Physiology, Faculty of Biology, University of Warmia and Mazury in Olsztyn, Oczapowski 1A, 10-718 Olsztyn, Poland.
Theriogenology. 2008 Feb;69(3):283-9. doi: 10.1016/j.theriogenology.2007.09.023. Epub 2007 Oct 30.
Past studies of the source of estrogens secreted during maternal recognition of pregnancy in pigs have focused on embryonic rather than uterine origin of these steroids. The present study documents: (1) the expression of the gene CYP 17, encoding cytochrome P450 17alpha-hydroxylase/C(17-20) lyase and (2) the synthesis and secretion of estradiol-17 beta (E(2)) in endometrial and myometrial tissues in gilts. The expression of CYP 17 gene was shown in porcine endometrium and myometrium. Basal endometrial secretion of E(2) was higher in pregnant gilts than in cyclic gilts (days 14-16). The myometrium secreted more E(2) during the expected time of luteolysis compared to early pregnancy. Basal secretion of E(2) during pregnancy was higher from the endometrium than from the myometrium. Conversely, during luteolysis E(2) secretion was higher from the myometrium and lower from the endometrium. In pregnant and cyclic gilts (days 14-16), progesterone (P(4), 10(-5)M) in vitro significantly increased E(2) secretion regardless of reproductive status. Oxytocin (OT, 10(-7)M) had no influence on E(2) secretion and did not change the stimulatory effect of P(4) in both tissues examined. In conclusions: (1) the CYP 17 gene transcript is present in porcine endometrium and myometrium; (2) porcine endometrium and myometrium release E(2) in vitro; (3) the endometrium releases more E(2) than the myometrium during early pregnancy; (4) the myometrium releases E(2) mainly during luteolysis; (5) the endometrium and myometrium can increase E(2) release in vitro if substrate (P(4)) is provided during early pregnancy and luteolysis. These data suggest active estrogen production by the myometrium and endometrium as an alternative source for this signal for recognition of pregnancy in the pig.
过去关于母猪妊娠识别期间分泌雌激素来源的研究主要集中在这些类固醇的胚胎来源而非子宫来源。本研究记录了：（1）编码细胞色素P450 17α-羟化酶/C（17-20）裂解酶的CYP 17基因的表达，以及（2）后备母猪子宫内膜和子宫肌层组织中雌二醇-17β（E₂）的合成与分泌。CYP 17基因在猪子宫内膜和子宫肌层中表达。妊娠后备母猪的子宫内膜基础E₂分泌高于发情周期的后备母猪（第14-16天）。与妊娠早期相比，子宫肌层在预期黄体溶解期分泌更多的E₂。妊娠期间子宫内膜的E₂基础分泌高于子宫肌层。相反，在黄体溶解期，子宫肌层的E₂分泌较高，而子宫内膜的E₂分泌较低。在妊娠和发情周期的后备母猪（第14-16天）中，体外添加孕酮（P₄，10⁻⁵M）无论生殖状态如何均显著增加E₂分泌。催产素（OT，10⁻⁷M）对E₂分泌无影响，且不改变两种检测组织中P₄的刺激作用。结论如下：（1）CYP 17基因转录本存在于猪子宫内膜和子宫肌层中；（2）猪子宫内膜和子宫肌层在体外释放E₂；（3）妊娠早期子宫内膜释放的E₂比子宫肌层多；（4）子宫肌层主要在黄体溶解期释放E₂；（5）如果在妊娠早期和黄体溶解期提供底物（P₄），子宫内膜和子宫肌层可在体外增加E₂释放。这些数据表明子宫肌层和子宫内膜可产生活性雌激素，作为猪妊娠识别信号的另一种来源。
