Background: Estrogen receptor (ER)-mediated effects have been associated with the modulation of myocardial hypertrophy in animal models and in humans, but ER expression in the human heart and its relation to hypertrophy-mediated gene expression have not yet been analyzed. We therefore investigated sex- and disease-dependent alterations of myocardial ER expression in human aortic stenosis together with the expression of hypertrophy-related genes.
Methods and results: ER-alpha and -beta, calcineurin A-beta, and brain natriuretic peptide (BNP) mRNA were quantified by real-time polymerase chain reaction in left ventricular biopsies from patients with aortic valve stenosis (n=14) and control hearts with normal systolic function (n=17). ER protein was quantified by immunoblotting and visualized by immunofluorescence confocal microscopy. ER-alpha mRNA and protein were increased 2.6-fold (P=0.003) and 1.7-fold (P=0.026), respectively, in patients with aortic valve stenosis. Left ventricular ER-beta mRNA was increased 2.6-fold in patients with aortic valve stenosis (P<0.0001). ER-alpha and -beta were found in the cytoplasm and nuclei of human hearts. A strong inverse correlation exists between ER-beta and calcineurin A-beta mRNA in patients with aortic valve stenosis (r=-0.83, P=0.002) but not between ER-alpha or -beta and BNP mRNA.
Conclusions: ER-alpha and -beta in the human heart are upregulated by myocardial pressure load.