Protective effect of estrogens against oxidative damage to heart and skeletal muscle in vivo and in vitro

Estrogen has been shown to protect skeletal muscle from damage and to exert antioxidant properties. The purpose of the present study was to investigat e the antioxidant and protective properties of estrogens in rodent cardiac and skeletal muscle and H9c2 cells. Female Sprague-Dawley rats were separat ed into three groups, ovariectomized (OVX), ovariectomized with estrogen re placement (OVX + E2), and intact control (SHAM), and were assessed at two t ime periods, 4 and 8 weeks. Rodents hearts were analyzed for basal and iron -stimulated lipid peroxidation in the absence and presence of beta-estradio l (beta E2) by measuring thiobarbituric acid reactive species (TBARS), Isol ated soleus (SOL) and extensor digitorum longus (EDL) were analyzed for cre atine kinase (CK) efflux, Using H9c2 cells, the in vitro effects of beta E2 and its isomer alpha-estradiol were investigated under glucose-free/hypoxi c conditions. TBARS assay was also performed on the H9c2 in the presence or absence of beta E2, The results indicate that OVX rodent hearts are more s usceptible to lipid peroxidation than OVX + E2 hearts. OVX soleus showed hi gher cumulative efflux of CK than OVX + E2, Furthermore, H9c2 survival duri ng oxidative stress was enhanced when estrogen was present, and both OVX he arts at 4 weeks and H9c2 cells particularly were protected from oxidative d amage by estrogens. We conclude that estrogen protects both skeletal and ca rdiac muscle from damage, and its antioxidant activity can contribute to th is protection.