Role of the Renin-Angiotensin System in Healthy and Pathological Pregnancies

Abstract

Introduction: Pregnancy is a physiological process that necessitates many cardiovascular and hemodynamic adaptations to ensure the survival of the foetus and well-being of the mother. The renin-angiotensin system (RAS) has been suggested as key player in many of these changes as it is critical for blood pressure control as well as fluid and salt homeostasis in the non-pregnant state. Body: Normal pregnancy is characterized by an increase in the circulating levels of prorenin, renin, angiotensinogen and angiotensin-II. However, this is coupled to a diminished endothelial sensitivity to angiotensin-II, which may explain the lack of increase in blood pressure in pregnancy. Conversely, an increase in circulating levels of aldosterone and anti-diuretic hormone during pregnancy can be observed and could contribute to the enhanced renal sodium and water reabsorption, respectively. Moreover, dysregulation of the RAS has been implicated in the development of gestational hypertensive disorders such as preeclampsia. Conclusion: The difference in the RAS effects observed during normal pregnancy may be attributable to local modifications of the RAS as well as to non-classic RAS such as the angiotensin-(1-7) axis. These adaptations may be dysregulated during preeclampsia and may contribute to the development of the disease.

Endocrine disorders and fertility and pregnancy: An update

“…During physiological pregnancy, aldosterone levels increase, inducing elevated plasma volume, which is essential for the maintenance of circulating blood volume, blood pressure, and uteroplacental perfusion. Aldosterone levels remain high throughout pregnancy, suggesting a possible role in the regulation of placental and fetal development ( 198 , 199 ). Recent studies have shown the possible involvement of aldosterone in some gynecological conditions and diseases, including endometriosis combined with infertility.…”

“…Recent studies have shown the possible involvement of aldosterone in some gynecological conditions and diseases, including endometriosis combined with infertility. Aldosterone may exacerbate systemic and local inflammatory states underlying endometriosis by activating mineralocorticoid receptors present in inflammatory cells ( 198 ).…”

Scientific Evidences Supporting the Activation of the Renin-Angiotensin-Aldosterone System during Estral Cycle and Pregnancy in Mares

“…The placenta appears to be the major source for the conversion of angiotensin I into ANG-II, since the prorenin, active renin, angiotensin converting enzyme (ACE), and ANG-II have been identified in the chorion and in the placenta [88]. The physiological roles of these components have not been completely clarified, but it has been speculated that they might participate in the regulation of the blood flow [89][90][91][92].…”