Local intra-uterine Ang-(1-7) infusion attenuates PGE2 and 6-keto PGF1α in decidualized uterus of pseudopregnant rats

Background: Cyclooxygenase (COX)-derived prostanoids (PGE2, PGI2) are important contributors to the process of decidualization. Previous studies showed the presence of Ang-(1-7) in the primary and secondary decidualized zones of the implantation site at early pregnancy. Decreased concentrations of Ang-(1-7) were found in the decidualized uterus compared to the non-decidualized uterus of pseudopregnant rats, suggesting that low levels of Ang-(1-7) are required for successful decidualization at early pregnancy. Methods: To understand the role of Ang-(1-7) in prostaglandin production in a decidualized uterus, induced by a bolus injection of sesame oil, Ang-(1-7) (24 μg/kg/h) or vehicle was then infused directly into the decidualized uterine horn using an osmotic minipump. The right horns were not injected or infused and served as nondecidualized uterine horns in both groups of animals. Results: Decidualization increased PGE2 concentration in the uterus (0.53±0.05 vs. 12.0±3.2 pmol/mg protein, p\u3c0.001, non-decidualized vs. decidualized horns); Ang-(1-7) infusion attenuated the increase of PGE2 (12.0± 3.2 vs. 5.1±1.3 pmol/mg protein, p\u3c0.01 control vs. Ang-(1-7) treated decidualized horns). The stable metabolite of PGI2 (6-keto PGF1α) was increased with decidualization (0.79±0.17 vs. 3.5±0.82 pmol/mg protein, p\u3c0.001, non-decidualized vs. decidualized horns). Ang-(1-7) infusion attenuated the increase in 6keto PGF1α in the decidualized horn (3.5±0.82 vs 1.8±0.37 pmol/mg protein, p\u3c0.05 control vs. Ang-(1-7) treated decidualized horns). The circulating levels of 6-keto-PGF1a and TXB2 were decreased by Ang-(1-7) infusion, while no difference was observed in circulating PGE2. Although the global assessment of cleaved caspase 3 immunostaining, a marker of apoptosis, was unchanged within the Ang-(1-7) decidualized horn, there were localized decreases in cleaved caspase 3 staining in the luminal region in the decidualized uterus of Ang-(1-7)-treated rats. Conclusions: These studies show that increased local uterine Ang-(1-7) alters the uterine prostaglandin environment, possibly leading to disruptions of early events of decidualization

Effects of Circulating and Local Uteroplacental Angiotensin II in Rat Pregnancy.

The renin-angiotensin (Ang) system is important during placental development. Dysregulation of the renin-Ang system is important in preeclampsia (PE). Female rats transgenic for the human angiotensinogen gene crossed with males transgenic for the human renin gene develop the PE syndrome, whereas those of the opposite cross do not. We used this model to study the role of Ang II in trophoblast invasion, which is shallow in human PE but deeper in this model. We investigated the following groups: PE rats, opposite-cross rats, Ang II–infused rats (1000 ng/kg per day), and control rats. Ang II infusion increased only circulating Ang II levels (267.82 pg/mL), opposite cross influenced only uteroplacental Ang II (13.52 fmol/mg of protein), and PE increased both circulating (251.09 pg/mL) and uteroplacental (19.24 fmol/mg of protein) Ang II. Blood pressure and albuminuria occurred in the models with high circulating Ang II but not in the other models. Trophoblast invasion increased in PE and opposite-cross rats but not in Ang II–infused rats. Correspondingly, uterine artery resistance index increased in Ang II–infused rats but decreased in PE rats. We then studied human trophoblasts and villous explants from first-trimester pregnancies with time-lapse microscopy. Local Ang II dose-dependently increased migration by 75%, invasion by 58%, and motility by 282%. The data suggest that local tissue Ang II stimulates trophoblast invasion in vivo in the rat and in vitro in human cells, a hitherto fore unrecognized function. Conceivably, upregulation of tissue Ang II in the maternal part of the placenta represents an important growth factor for trophoblast invasion and migration

Local uterine Ang-(1-7) infusion augments the expression of cannabinoid receptors and differentially alters endocannabinoid metabolizing enzymes in the decidualized uterus of pseudopregnant rats

Background Endocannabinoids (ECs) are important contributors to implantation and decidualization and are suppressed in early pregnancy. Elevated levels of anandamide (AEA), the endogenous ligand for the CB1 and CB2 receptors (R), interfere with receptivity of the blastocyst. Ang-(1–7) is down-regulated in the implantation site (IS) in normal pregnancy at day 7 of gestation. We determined the effects of intra-uterine angiotensin-(1–7) [Ang-(1–7)] (24 microg/kg/h) or vehicle given into the left uterine horn on the ECs in the decidualized uterus. Methods Ovariectomized rats were sensitized for the decidual cell reaction by steroid treatment and decidualization was induced by a bolus of oil injected into the left horn; the right horn served as a control. Results Decidualization increased endometrial permeability (3.1+/−0.2 vs. 7.1+/−0.5 uterus/muscle of cpm of (125)I-BSA, p \u3c 0.0001). VEGF mRNA was increased by the decidualization (1.4-fold, p \u3c 0.05) and by Ang-(1–7) (2.0-fold, p \u3c 0.001). CB1R mRNA was reduced by decidualization (2.7-fold, p \u3c 0.001), but increased by Ang-(1–7) (1.9-fold, p \u3c 0.05). CB2R mRNA was increased by decidualization (4-fold, p \u3c 0.05) and by Ang-(1–7) (2.4-fold, p \u3c 0.001). The enzyme metabolizing AEA, fatty acid amide hydrolase (FAAH), was reduced by decidualization (7.8 fold, p \u3c 0.001) and unchanged by Ang-(1–7) (p \u3e 0.05), whereas the enzyme metabolizing 2-arachidonoylglycerol, monoacyl glycerol lipase (MAGL), was unchanged by decidualization (p \u3e 0.05) and increased by Ang-(1–7) (1.7 fold, p \u3c 0.001). Conclusions These findings report for the first time that Ang-(1–7) augments the expression of CB1R, CB2R and MAGL in the decidualized uterus and thus may interfere with the early events of decidualization

Tissue-specific regulation of ACE/ACE2 and AT 1 /AT 2 receptor gene expression by oestrogen in apolipoprotein E/oestrogen receptor-α knock-out mice: Oestrogen regulation of ACE/ACE2 and AT1/AT2

ACE and ACE2 and the AT1 and AT2 receptors are pivotal points of regulation in the renin-angiotensin system. ACE and ACE2 are key enzymes in the formation and degradation of Ang II and Ang-(1-7). Ang II acts at either the AT1 or the AT2 receptor to mediate opposing actions of vasoconstriction/vasodilation. While it is known that estrogen (E2) acts to down-regulate ACE and the AT1 receptors, its regulation of ACE2 and the AT2 receptor and the involvement of a specific estrogen receptor subtype are unknown. To investigate the role of estrogen receptor-α (ERα) in estrogen’s regulation of ACE/ACE2 and AT1/AT2 mRNAs in lung and kidney, ovariectomized female mice lacking apolipoprotein E (ee) with the ERα (AAee) or without the ERα (ααee) were treated with 17-β estradiol (6 µg/day) or placebo for 3 months. ACE,ACE2 and AT1/AT2 receptor mRNAs were measured using reverse transcriptase, real-time polymerase chain reaction (RT/RT-PCR). In the kidney, 17-β estradiol showed 1.7 fold down-regulation of ACE mRNA in AAee mice, with 2.1-fold up-regulation of ACE mRNA in ααee mice. 17-β estradiol showed 1.5 and 1.8 fold down-regulation of ACE2 and AT1 receptor mRNA in AAee mice; this regulation was lost in ααee mice. 17-β estradiol showed marked (81-fold) up-regulation of the AT2 receptor mRNA in AAee mice. In the lung 17-β estradiol treatment had no effect on AT1 receptor mRNA in AAee mice, but resulted in a 1.5-fold decreased regulation of AT1 mRNA in ααee. There was no significant interaction of estrogen with ER in the lung for ACE, ACE2, and AT2 receptor genes. These studies reveal tissue specific regulation by 17-β estradiol of ACE/ACE2 and AT1/AT2 receptor genes with the ERα receptor primarily responsible for the regulation of kidney ACE2 , AT1 receptor, and AT2 receptor genes

Vasodilator factors in the systemic and local adaptations to pregnancy

We postulate that an orchestrated network composed of various vasodilatory systems participates in the systemic and local hemodynamic adaptations in pregnancy. The temporal patterns of increase in the circulating and urinary levels of five vasodilator factors/systems, prostacyclin, nitric oxide, kallikrein, angiotensin-(1–7) and VEGF, in normal pregnant women and animals, as well as the changes observed in preeclamptic pregnancies support their functional role in maintaining normotension by opposing the vasoconstrictor systems. In addition, the expression of these vasodilators in the different trophoblastic subtypes in various species supports their role in the transformation of the uterine arteries. Moreover, their expression in the fetal endothelium and in the syncytiotrophoblast in humans, rats and guinea-pigs, favour their participation in maintaining the uteroplacental circulation. The findings that sustain the functional associations of the various vasodilators, and their participation by endocrine, paracrine and autocrine regulation of the systemic and local vasoactive changes of pregnancy are abundant and compelling. However, further elucidation of the role of the various players is hampered by methodological problems. Among these difficulties is the complexity of the interactions between the different factors, the likelihood that experimental alterations induced in one system may be compensated by the other players of the network, and the possibility that data obtained by manipulating single factors in vitro or in animal studies may be difficult to translate to the human. In addition, the impossibility of sampling the uteroplacental interface along normal pregnancy precludes obtaining longitudinal profiles of the various players. Nevertheless, the possibility of improving maternal blood pressure regulation, trophoblast invasion and uteroplacental flow by enhancing vasodilation (e.g. L-arginine, NO donors, VEGF transfection) deserves unravelling the intricate association of vasoactive factors and the systemic and local adaptations to pregnancy

Local uterine Ang-(1–7) infusion augments the expression of cannabinoid receptors and differentially alters endocannabinoid metabolizing enzymes in the decidualized uterus of pseudopregnant rats

Background Endocannabinoids (ECs) are important contributors to implantation and decidualization and are suppressed in early pregnancy. Elevated levels of anandamide (AEA), the endogenous ligand for the CB1 and CB2 receptors (R), interfere with receptivity of the blastocyst. Ang-(1–7) is down-regulated in the implantation site (IS) in normal pregnancy at day 7 of gestation. We determined the effects of intra-uterine angiotensin-(1–7) [Ang-(1–7)] (24 microg/kg/h) or vehicle given into the left uterine horn on the ECs in the decidualized uterus. Methods Ovariectomized rats were sensitized for the decidual cell reaction by steroid treatment and decidualization was induced by a bolus of oil injected into the left horn; the right horn served as a control. Results Decidualization increased endometrial permeability (3.1+/−0.2 vs. 7.1+/−0.5 uterus/muscle of cpm of (125)I-BSA, p \u3c 0.0001). VEGF mRNA was increased by the decidualization (1.4-fold, p \u3c 0.05) and by Ang-(1–7) (2.0-fold, p \u3c 0.001). CB1R mRNA was reduced by decidualization (2.7-fold, p \u3c 0.001), but increased by Ang-(1–7) (1.9-fold, p \u3c 0.05). CB2R mRNA was increased by decidualization (4-fold, p \u3c 0.05) and by Ang-(1–7) (2.4-fold, p \u3c 0.001). The enzyme metabolizing AEA, fatty acid amide hydrolase (FAAH), was reduced by decidualization (7.8 fold, p \u3c 0.001) and unchanged by Ang-(1–7) (p \u3e 0.05), whereas the enzyme metabolizing 2-arachidonoylglycerol, monoacyl glycerol lipase (MAGL), was unchanged by decidualization (p \u3e 0.05) and increased by Ang-(1–7) (1.7 fold, p \u3c 0.001). Conclusions These findings report for the first time that Ang-(1–7) augments the expression of CB1R, CB2R and MAGL in the decidualized uterus and thus may interfere with the early events of decidualization