Combined effects of 17β-estradiol and exercise training on cardiac apoptosis in ovariectomized rats

Background The purpose of this study was to investigate the combined 17 beta-estradiol (E2) and exercise training on cardiac pro-survival and anti-apoptotic pathways in ovariectomized rats. Methods Fifty-six female Sprague-Dawley rats were divided into a sham-operated (Sham), a bilaterally ovariectomized (OVX), an OVX treated with E2 (OVX-E2; 10 mu g/kg/day), and an OVX with E2 and treadmill exercise training (OVX-E2-EX; 60 min/day, 5 days/week) for 10 weeks. Following 10 weeks of exercise training, rat hearts were isolated for the evaluation of Histopathological analysis, TUNEL assay, and Western blotting. Results The protein levels of estrogen receptor alpha (ER alpha), estrogen receptor beta (ER beta), insulin-like growth factor 1 (IGF-1), IGF-1 receptor (IGF-1 R), phospho-phosphatidylinositol 3-kinase (pP13K) (estrogen receptors/IGF-1-related survival pathway) were significantly increased in either the OVX-E2 or OVX-E2-EX group when compared with the OVX group. The protein levels of B-cell lymphoma 2 (Bcl-2), B-cell lymphoma-extra-large (Bcl-xL) and phosphorylated-Bad (p-Bad) (Bcl-2 family survival pathway) were significantly increased in the OVX-E2 group when compared with the OVX group. Only the p-Bad was significantly increased in the OVX-E2 group when compared with the OVX group. The protein levels of truncation of Bid (t-Bid), Bcl-2-associated death promotor (Bad), Bcl-2-associated X protein (Bax), Cytochrome c, caspases-9, and caspases-3 (mitochondria-dependent apoptotic pathway), as well as the protein levels of tumor necrosis factor-a (TNF-alpha), Fas ligand, Fas receptors, Fas-associated death domain (FADD), activated caspase-8 and activated caspase-3 (Fas receptor-dependent apoptotic pathway) were significantly decreased in either the OVX-E2 or OVX-E2-EX group when compared with the OVX group. Furthermore, when compared with the OVX-E2 group, the protein levels of ER beta, IGF-1, IGF-1R, Bcl-2 and BclxL were further enhanced in the OVX-E2-EX group as well as the protein levels of Cytochrome c, Fas receptors, FADD, activated caspase-8, activated caspase-9 and activated caspase-3 were further decreased in the OVX-EX-E2 group. Conclusions Combined E2 and exercise training exhibited a positive effect of protection on ovariectomy-induced cardiac apoptosis by enhancing ER beta-related survival pathways, which might provide a more effective therapeutic effect on cardiac protection in bilaterally oophorectomized or menopausal women than E2 treatment only.