Placental contribution to the endocrinology of gestation and parturition

Abstract

In addition to many other functions, the placenta is a source of a vast number of autocrine, paracrine and endocrine factors. However, the spectrum of placental regulatory factors, their concentrations, gestational profiles and roles may differ considerably even between phylogenetically closely related species. Depending on the species, placental regulatory factors of a broad range of molecule classes have been found including (glyco-)proteins, peptides, steroids and prostaglandins. Local placental regulatory factors are especially important for the dialogue between the fetal and the maternal compartment immediately at the feto-maternal borderline and for the control of growth, differentiation and functions of the placenta itself. Moreover, placental hormones in a proper sense may also have effects in more remote targets within the maternal compartment, serving functions such as pregnancy-specific adaptations of maternal circulation, provision of hemotrophe to the fetus or the development and function of the mammary gland. Functions of placental hormones in the fetus proper are less clear but may be especially important before the establishment of a functional fetal endocrine system and near term within the highly species-specific networks of signals preparing and initiating parturition. This review takes a comparative view on the situation in different domestic animals focusing on ruminants and on placental hormones occurring at significant concentrations in the maternal circulation.

Expression of C–C motif chemokines and their receptors in bovine placentomes at spontaneous and induced parturition

“…These findings suggest that CCLs contribute to decreasing PG production and preventing luteolysis during early pregnancy in cows. However, luteolysis by PGF2α is regarded as a prerequisite for the onset of parturition in cows [21]. Additionally, placentomal PG production and conversion from progesterone to estrogen are augmented as parturition progresses [22,23].…”

“…Thus, it appears that glucocorticoids are indirectly involved in the increase in CCR1 expression in bovine placentomes at parturition. In spontaneous parturition, increased cortisol release from the fetal adrenals stimulates PGE2 and estrogen synthesis in the cotyledons [21,26]. The inflammatory activities of PGE2 and estrogen might be involved in regulation of the CCL-CCR system in placentomes.…”

Trophoblast cell differentiation in the bovine placenta: differentially expressed genes between uninucleate trophoblast cells and trophoblast giant cells are involved in the composition and remodeling of the extracellular matrix and O-glycan biosynthesis

“…The bovine placenta is capable of producing estrogens independently of the external supply of C19 precursors, as it expresses all enzymes needed to convert cholesterol into estrogens: side chain cleavage enzyme (CYP11A1), steroid 17-alpha-hydroxylase/17,20 lyase (CYP17A1), 3 beta-hydroxysteroid dehydrogenase/Delta 5➔4-isomerase (HSD3B1) and aromatase (CYP19A1) (reviewed by [2]). We searched our microarray data for the expression of the respective transcripts and found that all were downregulated in TGCs (Additional file 1: Table S1-A) The KEGG pathways and the associated DEGs are shown in the Additional file 1: Table S1-D [18] used immunoelectron microscopy and detected CYP11A1-specific signals only in UTCs, and CYP17A1 was immunolocalized only in UTCs [19].…”

“…The GH/PRL hormones regulate numerous physiological processes related to reproduction and lactation in many mammalian species, including cattle [22]. The bovine GH/PRL gene family comprises one GH and one PRL gene each, both expressed in the pituitary gland, and derivatives of the PRL gene (CSH2, PRPs) expressed in the placenta [2,23,24]. The DEGs encoding placentaexpressed GH/PRL representatives were all upregulated in the TGCs (Table 4; Additional file 1: Table S1-A).…”

“…PL regulates reproductive physiological processes in the uterus and mammary gland and further promotes the release of nutrients from the maternal to the fetal compartment. Remarkably, the functions of PRP-I have not been determined to date (reviewed by [2]). The most conspicuous structures of the bovine placenta are the mushroomshaped placentomes, which are composed of the fetal chorion and the maternal caruncle.…”