The estrogen receptor-α agonist 16α-LE2 inhibits cardiac hypertrophy and improves hemodynamic function in estrogen-deficient spontaneously hypertensive rats

Objective: Cardiac mass increases with age and with declining estradiol serum levels in postmenopausal women. Although the non-selective estrogen receptor-alpha and -beta agonist 17 beta-estradiol attenuates cardiac hypertrophy in animal models and in observational studies, it remains unknown whether activation of a specific estrogen receptor subtype (ER alpha or ER beta) might give similar or divergent results. Therefore, we analyzed myocardial hypertropby as well as cardiac function and gene expression in ovariectomized, spontaneously hypertensive rats (SHR) treated with the subtype-selective ER alpha agonist 16 alpha-LE2 or 17 beta-estradiol. Methods and Results: Long-term administration of 16 alpha-LE2 or 17 beta-estradiol did not affect elevated blood pressure, but both agonists efficiently attenuated cardiac hypertrophy and increased cardiac output, left ventricular stroke volume, papillary muscle strip contractility, and cardiac a-myosin heavy chain expression. The observed effects of E2 and 16 alpha-LE2 were abrogated by the ER antagonist ZM-182780. Improved left ventricular function upon 16 alpha-LE2 treatment was also observed in cardiac MRI studies. In contrast to estradiol and 16 alpha-LE2, tamoxifen inhibited cardiac hypertrophy but failed to increase alpha-myosin heavy chain expression and cardiac output. Conclusions: These results support the hypothesis that activation of ER alpha favorably affects cardiac hypertrophy, myocardial contractility, and gene expression in ovariectornized SHR. Further studies are required to determine whether activation ER beta mediates redundant or divergent effects. (c) 2005 European Society of Cardiology. Published by Elsevier B.V. All rights reserved.