| 摘要: | To identify the cardioprotective effects of 17b-estradiol (E2) and estrogen receptor a (ERa) from apoptosis induced by isoproterenol-activated b-adrenergic pathway, we established a Tet-On system, using doxycycline to induce ER-a overexpression in H9c2 cardiomyoblast cells. H9c2 cells were treated with isoproterenol (Iso) alone, or combined with E2, ERa (induced by doxycycline), E2 plus ERa, or BSA-E2. Treatment without Iso was used as a control. The results examined by DNA fragmentation, DAPI, MTT assay and TUNEL assay showed that apoptosis induced by Iso was reversed by the treatments of E2, ERa, E2 plus ERa or BSA-E2. Phosphorylated Akt and ERK1/2 of H9c2 cells were significantly increased following the treatments of E2, ERa, E2 plus ERa or BSA-E2. Interestingly, this increase was attenuated by the addition of LY294002 (PI3K inhibitor) and U0126 (MEK inhibitor), respectively, in these four treated groups. Furthermore, the decreased levels of the apoptotic proteins such as Bad, cytosolic cytochrome-c and active caspase 9 & 3 following the 4 treatments to the Iso-treaated H9c2 cells were also observed. Taken together, the inhibitory effect of E2 and ERa on b-adrenergic pathway-induced apoptosis in H9c2 cardiomyoblast cells is mediated by activating PI3K/Akt and ERK1/2 pathways. |
