猪胚胎附植部分因子研究进展

A Review of Some Factors Related to Embryo Implantation in Pigs

产仔数性状是养猪业中一个重要的经济性状,而胚胎附植对猪产仔数的高低有重要的影响。胚胎附植的调控涉及到多个生物学过程,在其中发挥作用的物质(附植因子)很多。作者针对孕酮、孕酮受体、雌二醇、雌激素受体α(ESR1)和促红细胞生成素产生肝细胞受体配体(Eph-ephrin)系统这几种附植因子的相关研究进行了归纳总结,重点阐述了这些因子在母胎对话过程中的时空表达、功能、突变、调控等方面的研究进展。其中,孕酮及其受体在猪胚胎附植活动中全程发挥着重要作用,黄体分泌的孕酮与母猪子宫内膜腔上皮、腺上皮、基质和肌细胞中的孕酮受体结合发挥作用,使这些组织细胞分泌多种附植因子,这些附植因子进一步参与胚胎附植过程。雌二醇是雌激素中含量最多、活性最强的一种激素,主要由卵巢颗粒细胞分泌,雌激素受体α是子宫内雌二醇的主要受体,二者结合可使母猪发情;此外,附植中处于游离状态的胚泡也分泌雌二醇,其是一个让母猪子宫内膜得以识别的信号,允许胚泡附植。Eph-ephrin系统作用广泛,其在人、小鼠和猪的胚胎附植过程中发挥着重要作用。系统中的EphA1、ephrin A1、EphA4等基因在猪的胚胎附植期表达量显著高于空怀猪,它们在子宫内膜附植点的表达量显著高于附植点间的部位,且ephrin A1的抑制表达会降低子宫内膜上皮细胞的迁移和黏附能力。这些附植因子都在猪胚胎附植活动中发挥着重要作用,对它们的深入研究将有利于明确猪胚胎附植调控机理,进一步揭示猪高繁机理。

Litter size is a significant economic trait in pig industry,and embryo implantation plays an important role in the litter size of pigs.Regulation of embryo implantation involves many biological processes,in which there are many substances(implantation factors)play functions.In this study,the authors summarized the relevant researches on progesterone,progesterone receptor,estradiol,estrogen receptorα(ESR1)and erythropoietin-producing hepatocellular receptor-ligand(Eph-ephrin)system,and the paper is focused on the spatial and temporal expression,function,mutation and regulation of these factors during porcine embryo implantation.Among these implantation factors,progesterone and its receptor play an important role in the whole process of embryo implantation.Progesterone secreted by the corpus luteum combines with the progesterone receptors in the tissues of endometrial epithelium,glandular epithelium,stroma and muscle in the pregnant sows,and the combination stimulates cells of these tissues to secrete a variety of implantation factors,which are further involved in the embryo implantation process.Estradiol is one of the most abundant and active estrogens and it is mainly secreted by ovarian granulosa cells,and ESR1 is the main receptor of estradiol in uterus.Combination of estradiol and ESR1 can make the sow estrus.In addition,blastocyst in the free state also secretes estradiol,which is a signal that is allowed to be recognized by endometrium of the sow.Eph-ephrin system has an extensive function,including its role in regulation of embryo implantation in human,mouse and pigs.EphA 1,ephrin A 1 and EphA 4 genes of Eph-ephrin system have significantly higher expression in pregnant pigs during embryo implantation than that of non-pregnant pigs,and expression of these genes in endometrial attachment sites are significantly higher than that of inter-attachment sites.Besides,inhibition of ephrin A1 could reduce the migration and adhesion ability of endometrial epithelial cells.These implantation factors play important roles in porcine embryo implantation activities.In-depth researches on these factors will help to clarify the regulation mechanism of embryo attachment and further reveal the mechanism of high litter size in pigs.