107-POS

Abstract

Objectives In humans, angiotensin II type 1 and 2 receptors (AT1R and AT2R) have been implicated in trophoblast invasion and placental development. Since the utero-placental unit of guinea-pigs (GP) and humans share a morphologic structure, hormonal, vasodilator patterns and uterine spiral artery remodeling, this species was deemed suitable to study the spatio-temporal expression of the vasoconstrictive (AT1R) and vasodilator (AT2R) receptors of angiotensin II. Methods Utero-placental units were collected in days (D) 15, 20, 40 and 60 of a 64–67 days long pregnancy in Pirbright White guinea-pigs (n = 3 per period). The localization and intensity of expression of AT1R and AT2R in different structures of utero-placental units was evaluated by immunohistochemistry. Additionally immunogold electron microscopy for both receptors was performed in day 60. Results AT1R and AT2R were detected along pregnancy in the interlobium, the endothelium and syncytiotrophoblast of the placental labyrinth, subplacenta, giant cells, syncytial streamers, decidua, vascular smooth muscle of spiral arteries and myometrium; in day 20 in perivascular and intramural trophoblasts, while in late pregnancy these were observed in endoluminal trophoblasts in lateral and myometrial spiral arteries. The immunoreactivity of AT1R and AT2R was prominent in D15 in syncytial streamers and in D40 in intramural and intraluminal trophoblasts. Immunoelectron microscopy in D60 demonstrated both receptors in cell membrane, cytosol (cyt) and nucleus (nu) in the placenta (Figure). Conclusions The spatial pattern of AT1R and AT2R supports their association with decidualization, trophoblast invasion, vascular remodeling. This similarity with the human, added to an analogous intracellular localization of AT1R, validates the use of guinea-pigs to understand the local adaptations of pregnancy. Supported by Fondecyt 1121161 Disclosures S. Acuna: None. G. Valdes: None.