Abstract Body: Background: Alcohol triggers exacerbated cardiovascular effects in females, compared to males, in estrogen (E2) dependent manner. E2 provides cardiac protection in premenopausal women and models of menopause, yet the interplay between the circadian clock proteins and E2 in the female heart, particularly in the presence of ethanol (EtOH) remains unclear.
Aim: This study aims to determine if the suppression of the circadian clock protein Period 2 (Per2) and associated redox enzymes contribute to E2-mediated exacerbation of the EtOH-induced cardiac ferroptosis, and dysfunction.
Methods: Two groups of female Sprague-Dawley rats (n=6-8) were subjected to bilateral ovariectomy (OVX) and fed with EtOH (5% in liquid diet) in the presence of E2 or its vehicle for 8 weeks. Measurements of cardiac function using radiotelemetry and echocardiography along with ex vivo biochemical/molecular studies.
Results: Compared to vehicle treated OVX+EtOH group, the E2-treated OVX+EtOH group exhibited: (1) reduced (p<0.05) body weight gain and fat mass; (2) higher (p<0.05) telemetry-measured blood pressure and heart rate; (3) reductions (p<0.05) in echocardiography derived contractility indices, ejection fraction and fractional shortening. In the same group, ex vivo molecular analysis demonstrated: (1) lower cardiac Per2 and suppressed (p<0.05) redox enzymes; (2) increased (p<0.05) ROS level and glutathione depletion (p<0.05), leading to the degradation of glutathione peroxidase 4 (GPX4); (3) heme oxygenase-1 upregulation leading to iron overload (p<0.05). These ferroptosis-related effects resulted in increased lipid peroxidation (p<0.05) compared to findings in OVX+EtOH rats in the absence of E2.
Conclusion: This study is the first to suggest that abrogation of the E2-mediated Per2 upregulation unraveled cardiac ferroptosis and contributes to the detrimental cardiac effects of ethanol in E2-replete rats. These novel findings underscore the potential risk for myocardial ferroptosis and dysfunction in menopausal women who are consuming ethanol while on E2 replacement therapy.