Estrogen replacement restores period 2-mediated inhibition of ferroptosis and mitigates cardiac dysfunction in estrogen-deficient rats.

The ovarian hormone 17β-estradiol (E2) confers cardioprotection via upregulating cardiac circadian rhythm period 2 (Per2) and is associated cardioprotective microRNA (miRNAs). However, whether Per2-mediated downregulation of ferroptosis-induced oxidative stress and injury in noncardiac tissues extends to the heart remains unknown. Therefore, studying the interplay between E2 and cardiac ferroptosis will have important ramifications for female cardiovascular health. We hypothesized that Per2-mediated suppression of cardiac ferroptosis contributes to E2-dependent cardioprotection while E2 deficiency promotes ferroptosis and cardiac dysfunction in female rats. The study used Sprague-Dawley rats with sham operation (sham), bilateral ovariectomy (E2-deficient) followed by E2 or vehicle treatment for 8 weeks. Cardiovascular function was assessed via radiotelemetry and echocardiography, with ex vivo analyses of ferroptosis markers, Per2, and associated miRNAs in heart tissues. E2-replete (sham and ovariectomy + E2) rats showed lower body weight gain, heart weight/body weight ratio, fat mass, and blood pressure compared with E2-deficient rats. Echocardiography data revealed reduced contractility indices in E2-deficient rats, which were restored to sham levels with E2 treatment. Molecular analyses revealed that E2-treated E2-deficient rats had upregulated Per2, cardioprotective miRNAs (499, 192, 194, and 144), and improved redox balance, along with decreased cardiodetrimental miRNAs (652 and 208b) and reactive oxygen species. In E2-deficient rats, glutathione depletion led to reduced glutathione peroxidase-4, iron overload from heme oxygenase-1 upregulation, and increased lipid peroxidation. This study highlights possible contribution of Per2-mediated inhibition of ferroptosis to E2-mediated cardioprotection in females, offering new insights for women's heart health. SIGNIFICANCE STATEMENT: This study describes the contribution of estrogen-mediated upregulation of cardiac circadian clock protein Per2 to the inhibition of ferroptosis and the improvement of cardiac function. The findings offer new perspective for understanding the intersection between hormonal regulation, circadian clock protein, microRNA, and ferroptosis in cardiovascular health. The research adds new knowledge on female molecular cardiology, particularly those related to ferroptosis. This perspective broadens current understanding of the complex molecular underpinnings of female heart health in presence or absence of estrogen.