Aqueous extract of Cortex Dictamni protects H9c2 cardiomyocytes from hypoxia/reoxygenation-induced oxidative stress and apoptosis by PI3K/Akt signaling pathway.

Ischemia-reperfusion injury is the major manifestation of ischemic heart disease, which facilitates cardiac arrhythmias, heart failure and death. Oxidative stress and apoptosis have been involved in the pathogenesis of myocardial ischemia-reperfusion injury. Modern pharmacological studies have indicated that the extracts and active compounds of Cortex Dictamni exhibit antioxidative and cardiovascular protective activities. This study was designed to investigate the protective effect of aqueous extract of Cortex Dictamni (CDAE) on regulating hypoxia/reoxygenation (H/R)-induced cardiomyocytes oxidative stress and apoptosis. H9c2 cardiomyocytes pretreatmented with CDAE for 24h were exposed to hypoxia/reoxygenation. Cell survival was measured by methyl thiazolyl tetrazolium (MTT) assay, and by the detections of lactate dehydrogenase (LDH) activity and cardiac troponin I (cTn-I) content in cultured supernatant. Cell apoptosis was measured by Hoechst 33342/propidium iodide (PI) staining, Annexin-V/PI staining, and terminal deoxynucleotidyl transferase-mediated dUTP nick end labelling (TUNEL) assay. Intracellular reactive oxygen species (ROS) production, superoxide dismutase (SOD) activity and malondialdehyde (MDA) level were measured to examine antioxidant activity. Mitochondrial membrane potential and release of cytochrome c were measured to examine mitochondrial changes. The expressions of anti-oxidant, pro-apoptosis and anti-apoptosis proteins were measured by performing western blotting assay. Inhibitor LY294002 was used to confirm the regulation effect of CDAE on PI3K/Akt signaling pathway. CDAE pretreatment prevents H/R-induced cardiomyocytes oxidative stress and apoptosis through activation of PI3K/Akt signaling pathway.