Mitochondria play an important role in 17β-estradiol attenuation of H2O2-induced rat endothelial cell apoptosis

Studies have shown salutary effects of 17β-estradiol following trauma-hemorrhage on different cell types. 17β-Estradiol also induces improved circulation via relaxation of the aorta and has an anti-apoptotic effect on endothelial cells. Because mitochondria play a pivotal role in apoptosis, we hypothesized that 17β-estradiol will maintain mitochondrial function and will have protective effects against H2O2-induced apoptosis in endothelial cells. Endothelial cells were isolated from rats' aorta and cultured in the presence or absence of H2O2, a potent inducer of apoptosis. In additional studies, endothelial cells were pretreated with 17β-estradiol. Flow cytometry analysis revealed H2O2-induced apoptosis in 80.9% of endothelial cells; however, prior treatment of endothelial cells with 17β-estradiol resulted in an ∼40% reduction in apoptosis. This protective effect of 17β-estradiol was abrogated when endothelial cells were cultured in the presence ICI-182780, indicating the involvement of estrogen receptor (...