17 beta-estradiol attenuates pressure overload-induced myocardial hypertrophy through regulating caveolin-3 protein in ovariectomized female rats.

Our findings indicate that in ovariectomized female rats abdominal aortic constriction led to significant increases in left ventricular mass, myocyte diameter and heart weight/body weight (HW/BW) value, and decreases in interventricular septal thickness at diastole (IVSd), left ventricular percent fractional shortening (FS) and ejection fraction (EF). These pathophysiological alterations were largely reversed by administration with 17β-estradiol for eight weeks. Furthermore, the enhanced expression of extracellular signal-regulated kinases 1/2 and decreased expression of caveolin-3 were found in left ventricle of AAC group. 17β-estradiol (E(2)) administration increased the expression of caveolin-3 and reduced the level of ERK phosphorylation in these pressure-overloaded rats. Moreover, in cultured neonatal rat cardiomyocytes, E(2) inhibited the hypertrophic response to angiotensin II. This effect was reinforced by the addition of extracellular signal-regulated kinases 1/2 inhibitor PD98059, but was impaired when the cells were pretreated with caveolae disruptor, methyl-β-cyclodextrin (M-β-CD). In conclusion, our data indicate that estrogen attenuates the hypertrophic response induced by pressure overload through down-regulation of extracellular signal-regulated kinases 1/2 phosphorylation and up-regulation of caveolin-3 expression.