Fertile women have lower blood pressure and cardiovascular risk than age-matched men, which suggests that estrogens exert cardiovascular protective effects. However, whether 17 ␤-estradiol (E2) blunts aldosterone secretion, and thereby affects the gender dimorphism of blood pressure, is unknown. We therefore sought for the estrogen receptor (ER) subtypes in human adrenocortical tissues ex vivo by performing gene and protein expression studies. We also investigated the effect of E2 on aldosterone synthesis and the involved receptors through in vitro functional experiments in the adrenocortical cells HAC15. We found that in the human adrenal cortex and aldosteroneproducing adenoma cells, the most expressed ERs were the ER␤ and the G protein-coupled receptor-1 (GPER-1), respectively. After selective ER␤ blockade, E2 (10 nmol/L) markedly increased both the expression of aldosterone synthase and the production of aldosterone (ϩ5-to 7-fold vs baseline, P Ͻ .001). Under the same condition, the GPER-1 receptor agonist 1-[4-(6-bromo-benzo (1, 3)dioxol-5-yl)-3a,4,5,9b-tetrahydro-3H-cyclopenta[c] quinolin-8-yl]-ethanone (G-1) (10 nmol/L) mimicked this effect, which was abrogated by cotreatment with either the GPER-1 receptor antagonist (3aS*,4R*,9bR*)-4-(6-Bro-mo-1,3-benzodioxol-5-yl)-3a,4,5,9b-3H-cyclopenta[c]quinoline (G-15), or a selective protein kinase A inhibitor 8-Bromo-2-monobutyryladenosine-3,5-cyclic monophosphorothioate, Rp-isomer. Silencing of the ER␤ significantly raised aldosterone synthase expression and aldosterone production. Conversely, silencing of the GPER-1 lowered aldosterone synthase gene and protein expression. Moreover, it blunted the stimulatory effect of E2 on aldosterone synthase that was seen during ER␤ blockade. These results support the conclusion that in humans, E2 inhibits aldosterone synthesis by acting via ER␤. Pharmacologic disinhibition of ER␤ unmasks a potent secretagogue effect of E2 that involves GPER-1 and protein kinase A signaling. (Endocrinology 155: 4296 -4304, 2014) F ertile women are at lower risk of cardiovascular (CV) events and have lower blood pressure (BP) values than age-matched men (1, 2); for example, among hypertensive patients recruited in the ONTARGET trial, women had a 22% lower risk for myocardial infarction than men (3). Therefore, estrogens can decrease BP and thereby CV risk,

The TASK-2 channel lower expression represents a hallmark of APA and is associated with a higher expression of hsa-miR-23 and hsa-miR-34. The ensuing blunted TASK-2 activity increased the production of aldosterone in vitro and the expression of steroidogenic acute regulatory protein and CYP11B2. Hence, the lower expression of TASK-2 channel in APA cells can explain high aldosterone secretion in human primary aldosteronism despite the suppression of angiotensin II, hypertension, and hypokalemia.

Background. Fertile women have lower blood pressure and are held to be at lower risk for cardiovascular events than age-matched man. However, whether this gender dimorphism involves a modulation of aldosterone synthesis by 17 beta-estradiol (E2) is unknown. Aims. i) To investigate estrogen receptor subtypes gene expression in the normal human adrenal cortex (NAC), in aldosterone producing adenoma (APA) and in a human adrenocortical carcinoma cell line (HAC15); ii) To assess the effect of E2 on aldosterone synthase (CYP11B2) gene expression and to identify the receptor subtypes involved in this effect. Methods. We measured the expression of alpha (ERa), beta (ERb) and of G protein-coupled receptor (GPER-1)-1 in NAC and in APA tissue, and in HAC15 cells by real time RT-PCR. After demonstration that HAC15 cells express ERa, ERb, and GPER-1 we stimulated cells with 10-7M E2 alone, or after ERb selective blockade with 10-5M tetrahydrochrysenediol (THC), ERa selective blockade with 10-5M MPP dihydrochloride (MPP), non selective ERa and ERb blockade with 10-5M ICI 182.780, or after selective GPER-1 receptor blockade with 10-5M G-15. The cells were also exposed to the GPER-1 agonist G-1, alone or in the presence of MPP, THC, or Fulvestrant, and/or G-15. Changes of expression of CYP11B2 mRNA, measured with RT RT-PCR, was the experimental endpoint. Results. The quantitative expression of estrogen receptor subtypes was ERb > GPER-1 >> ERα in NAC, GPER-1 > ERb> ERa in APA, and ERb>ERa=GPER-1 in HAC15 cells. E2 alone or on top of selective ERa antagonism did not alter CYP11B2 expression. By contrast, E2 significantly increased CYP11B2 expression (+500 to + 700% from baseline, p <0.001) after selective ERb antagonism, or combined ERa and ERb blockade. Likewise, G-1 markedly increased CYP11B2 gene after combined ERb blockade, an effect that was abolished by G15 co-treatment. Conclusion. E2 potently stimulates aldosterone synthase expression via GPER-1 subtype receptor activation when the ERb is blocked. The ERb-mediated tonic inhibition of aldosterone synthase could contribute to explaining both the lower BP and CV risk of fertile women and the increase of BP after when this tonic ERb-mediated inhibition wanes during menopause or estrogen-modulation treatment.