Objectives and aims: Transcriptional effects of estrogens are primarily mediated by the two nuclear estrogen receptors (ER), ERalpha and ERbeta. Both receptors are present in the vasculature and in the human heart and have been shown to act antiatherogenic and to be protective against the development of cardiac hypertrophy. The aim was to quantify ER mRNA expression in left ventricular specimens from patients with coronary heart disease (CHD, n=15) and dilated cardiomyopathy (CMP, n=38) and compare their levels with those from healthy heart donors (n=9). Additionally, a possible variation of ERmRNA expression in human hearts in respect to time of day was studied.
Methods and results: mRNA expression of both ER receptors was detected by real-time PCR in all of the human specimens. There was no difference in the relative quantity of the receptors between CHD and CMP patients. However, control specimens showed significant lower levels of either receptor in the healthy myocardium (p<.001 each). Analyzing the time dependency of receptor expression with a cosinor analysis showed a significant 8-hour period rhythm for ERbeta in CMP- but no rhythm in CHD patients. Due to the low patient number, rhythmic analysis was not possible in controls.
Conclusions: The increased ERalpha and ERbeta mRNA expression in left ventricular specimens from CHD and CMP patients might reflect a compensatory mechanism to counteract the decline in ventricular function. Furthermore, we provided evidence for a time dependent variation of ERbeta receptor expression in the human heart.
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