Inhibition of ROS-mediated activation Src-MAPK/AKT signaling by orientin alleviates H 2 O 2 -induced apoptosis in PC12 cells

Abstract

Purpose: Reactive oxygen species (ROS) are considered a direct cause of neurodegenerative diseases (NDDs). Drugs developed to target ROS are effective for the treatment of NDDs. Orientin is a pyrone glucoside extracted from Polygonum orientale, and it exhibits many pharmacological activities. In this study, we aimed to determine whether orientin could relieve hydrogen peroxide (H 2 O 2 )-induced neuronal apoptosis and to investigate the specific target of orientin. Materials and methods: In this study, the neuroprotective effect and its possible mechanisms of orientin in mouse pheochromocytoma cell line (PC12) cells stimulated by H 2 O 2 , establishing an oxidative stress model, were investigated. And we further tested the role of ROS in the neuroprotective effects of orientin. Results: Orientin (5–100 µg/mL) did not cause toxicity in PC12 cells but significantly decreased H 2 O 2 -induced reduction in PC12 cell viability, cell apoptosis rates, and nuclear condensation. It also inhibited the activation of caspase-3 and degradation of poly(ADP-ribose) polymerase (PARP). Under the stimulation of H 2 O 2 , MAPKs (ERK, JNK, and p38), AKT, and Src signaling proteins in PC12 cells were activated in a time-dependent manner. The application of inhibitors that were specific for MAPKs, AKT, and Src effectively alleviated H 2 O 2 -induced cell apoptosis. In addition, the Src inhibitor decreased the activation of MAPKs and AKT signaling. More importantly, orientin effectively decreased H 2 O 2 -induced phosphorylation of MAPKs, AKT, and Src signaling proteins. Finally, we confirmed that orientin effectively inhibited H 2 O 2 -induced accumulation of ROS in cells. In addition, ROS inhibitors blocked the Src-MAPKs/AKT signaling pathway-dependent cell apoptosis stimulated by H 2 O 2 . Conclusion: These results indicate that alleviation of H 2 O 2 -induced cell apoptosis by orientin is Src-MAPKs/AKT dependent. Overall, our study confirms that orientin alleviates H 2 O 2 -induced cell apoptosis by inhibiting the ROS-mediated activation of Src-MAPKs/AKT signaling.