[Effect of icariin on hypoxia/reoxygenation injury in neonatal rat cardiomyocytes].

Objective: To investigate the effect of icariin on myocardial hypoxia reoxygenation injury and the possible mechanism.

Methods: Neonatal Sprague-Dawley rat cardiomyocytes in primary culture were treated with different concentrations of icariin for 24 h prior to hypoxia/reoxygenation injury. Cardiomyocyte apoptosis was evaluated with Tunel staining. The expression levels of apoptosis proteins were detected by Western blotting. The nuclear translocation of p65 was evaluated by immunofluorescence. The p65 signaling pathway was also detected by Western blotting.

Results: Myocardial apoptosis rate significantly increased after hypoxia/reoxygenation (control: 1.5% ± 0.1%;

Model: 23.4% ± 1.3%, P<0.05). While icariin significantly reduced cardiomyocyte apoptosis induced by hypoxia/reoxygenation (1 µmol/L icariin: 7.2% ± 0.9%; 10 µmol/L icariin: 3.9% ± 0.8%, both P<0.05). Western blot showed that the expression levels of pro-apoptotic protein, Bax, increased significantly (control: 0.19 ± 0.05;

Model: 0.41 ± 0.03, P<0.05), while the expression of anti-apoptotic protein, B-Cell CLL/Lymphoma 2 (BCL-2), was significantly reduced (control: 0.15 ± 0.02;

Model: 0.03 ± 0.01, P<0.05) after hypoxia/reoxygenation. Notably, icariin reduced the expression of Bax (1 µmol/L icariin: 0.29 ± 0.01; 10 µmol/L icariin: 0.33 ± 0.03, both P<0.05) and increased expression of BCL-2 (1 µmol/L icariin: 0.10 ± 0.03; 10 µmol/L icariin: 0.11 ± 0.02, both P<0.05). Immunofluorescence showed that NFκB-p65 nuclear translocation in cardiomyocytes was increased after hypoxia/reoxygenation (control: 3.6% ± 0.5%;

Model: 89.5% ± 4.8%, P<0.05), while icariin reduced the nuclear translocation of p65 (1 µmol/L icariin: 32.6% ± 2.3%; 10 µmol/L icariin: 10.6% ± 1.0%, both P<0.05). Moreover, icariin reduced the activation of p65 and phosphorylation of IKBα induced by hypoxia/reoxygenation in cardiomyocytes.

Conclusion: Icariin can protect cardiomyocytes against hypoxia reoxygenation injury, which may be via blocking p65 signaling pathway.