Roberts R M, Murray M K, Burke M G, Ketcham C M, Bazer F W
Department of Animal Science, University of Missouri, Columbia 65211.
Adv Exp Med Biol. 1987;230:137-50. doi: 10.1007/978-1-4684-1297-0_8.
The uterus of the pig secretes large amounts of protein in response to progesterone. Estrogen alone has little effect but in combination with progesterone is synergistic at low doses and inhibitory at high doses. The responses of the uterus to progesterone require prolonged hormone treatment and are not immediate. The proteins secreted by the uterus of all species are believed to play some role in the nutritional and developmental support of the conceptuses, particularly during early pregnancy. Such a role is likely to be of greater importance in species such as the pig which possesses a noninvasive, diffuse-type of epitheliochorial placentation. A group of basic polypeptides dominates the uterine secretions of the pig. The best characterized is uteroferrin, a purple colored, iron-containing acid phosphatase which transports iron across the placenta. Three polypeptides which are found associated noncovalently with uteroferrin have been shown to be antigenically closely related to each other and to have arisen from a single precursor polypeptide. Their function is unknown. A family of plasmin/trypsin inhibitors which show sequence homology with bovine pancreatic trypsin inhibitor (aprotinin) has been well characterized and appears to control intrauterine proteolytic events initiated by the conceptuses. Several other proteins secreted in response to progesterone remain to be characterized and functionally defined.
猪的子宫会在孕酮的作用下分泌大量蛋白质。单独的雌激素作用很小，但与孕酮联合时，在低剂量下具有协同作用，在高剂量下具有抑制作用。子宫对孕酮的反应需要长时间的激素处理，并非即时生效。所有物种子宫分泌的蛋白质都被认为在对胎儿的营养和发育支持中发挥一定作用，尤其是在妊娠早期。在具有非侵入性、弥散型上皮绒毛膜胎盘的物种如猪中，这样的作用可能更为重要。一组碱性多肽在猪的子宫分泌物中占主导地位。最具特征的是子宫铁蛋白，一种紫色的含铁酸性磷酸酶，它能将铁转运过胎盘。已证明三种与子宫铁蛋白非共价结合的多肽彼此在抗原性上密切相关，且由单一前体多肽产生。它们的功能尚不清楚。一类与牛胰蛋白酶抑制剂（抑肽酶）具有序列同源性的纤溶酶/胰蛋白酶抑制剂已得到充分表征，似乎能控制由胎儿引发的子宫内蛋白水解事件。其他几种因孕酮分泌的蛋白质仍有待表征和确定其功能。
