Autoradiographic Localization and Characterization of Angiotensin II Receptors in the Bovine Placenta and Fetal Membranes1

Abstract

Autoradiography and angiotensin (Ang) II receptor binding studies showed that all parts of the bovine placenta and fetal membranes contained high densities of Ang II receptors throughout gestation. The receptors were predominantly subtype 2 (AT2) receptors in the fetal and subtype 1 (AT1) receptors in the maternal compartment. In the allantoamnionic membrane, Ang II receptors were evenly distributed in the mesenchymal tissue, with the highest expression around the few arteries. In the intercotyledonary and cotyledonary allantochorionic membrane, AT2 receptors as well as the less-expressed AT1 receptors were located on mesenchymal cells, especially adjacent to the allantoic endoderm, trophoblast cell layer, and arteries. In the mesenchymal tissue of the placentome, Ang II receptors were mostly expressed at the main branches of the fetal villi of the cotyledons. In the maternal part of the placentome, mainly AT1 receptors but also low densities of AT2 receptors and non-AT1/non-AT2 Ang II binding sites were found close to the stalk and at the main branches of the maternal crypts. Autoradiography revealed no changes in the pattern of distribution of the Ang II receptors throughout gestation. It is suggested that Ang II has an effect on regulatory as well as growth processes in these tissues.

Differential expression of angiotensin II type 1 and type 2 receptors at the maternal–fetal interface: potential roles in early placental development

“…We have also described the expression of AGTR1 and AGTR2 in trophoblast subpopulations at the maternal-fetal interface, with AGTR1 primarily expressed by the differentiated trophoblasts:syncytiotrophoblast and cell column extravillous trophoblasts, and AGTR2 by proliferating villous cytotrophoblasts. AGTR2 is abundantly expressed in murine, porcine and bovine placenta (Grady et al 1991, Nielsen et al 1996, Schauser et al 1998, and it is the predominant receptor present in human cycling endometrium and myometrium (Tsuzuki et al 1994, Ahmed et al 1995. However, previous reports in the literature of its expression in human placenta are conflicting (Cooper et al 1999, Anton et al 2008, Williams et al 2010.…”

Expression of Trophoblast Cell-Specific Pregnancy-Related Genes in Somatic Cell-Cloned Bovine Pregnancies1

“…NT and AI cows were slaughtered around Days 30, 60, and 100 of gestation. The endometrial and placental tissues were collected and separated as detailed by Nikitenko et al [35] and Regnault et al [36] and illustrated schematically by Schauser et al [37]. The endometrial tissue was separated into caruncular and intercaruncular areas for comparison during pregnancy.…”

Localization of the Renin-Angiotensin System in the Bovine Ovary: Cyclic Variation of the Angiotensin II Receptor Expression1

“…Cell membrane fractions for Ang II receptor binding studies were prepared as previously described in detail [21,23]. The membrane fractions were frozen at Ϫ20ЊC for later analysis.…”

“…The Ang II receptor assay was performed in a final volume of 150 l by incubation at 37ЊC for 1 h as described earlier [21,23]. The resuspended membrane fraction (100 l) was incubated with 25 l of 125 I- , were used as ligands as described before [23].…”

“…The resuspended membrane fraction (100 l) was incubated with 25 l of 125 I- , were used as ligands as described before [23]. After incubation for 1 h, 3 ml of ice-cold 10 mM sodium phosphate (pH 7.4) containing 120 mM sodium chloride was added, and the mixture was immediately filtered through Whatman GF/F glass fiber filters (Whatman, Clifton, NJ) presoaked with 2 g/L human serum albumin.…”