Protective effects of leonurine against ischemic stroke in mice by activating nuclear factor erythroid 2-related factor 2 pathway

Aims Leonurine has been shown to trigger antioxidant responses during ischemic stroke, and nuclear factor erythroid 2-related factor 2 (Nrf-2) imparts protective effects against oxidative injury. The present study has determined that leonurine prevents ischemic injury of brain tissues via Nrf-2 pathway activation. Methods Male ICR mice and Nrf-2(-/-) mice were subjected to permanent middle cerebral artery occlusion (pMCAO) and received leonurine treatment at 2 hours after pMCAO by intraperitoneal injection. Neurological deficit scores as well as infarct volume were assessed to determine the neuroprotective role of leonurine. Nrf-2 was investigated using Western blotting and real-time polymerase chain reaction (RT-PCR) analysis to elucidate the neuroprotective mechanism of leonurine. Commercial kits were employed to determine reactive oxygen species (ROS), superoxide (SOD), catalase (CAT), glutathione peroxidase (GSH-Px), malonaldehyde (MDA), and glutathione (GSH). Vascular endothelial growth factor (VEGF) was evaluated by Western blotting and RT-PCR analysis, and VEGF was localized using immunofluorescence. Results The application of leonurine on ICR mice resulted in an improvement in neurological deficit scores and a reduction in infarct volume. Leonurine upregulated nuclear Nrf-2 protein and increased total Nrf-2 protein expression and mRNA levels. Leonurine regulated SOD, MDA, CAT, GSH, and GSH-Px, and it significantly inhibited ROS production in ICR mice. Leonurine improved VEGF expression and increased VEGF expression in neurons, astrocytes, and endothelial cells. However, leonurine had no obvious beneficial effects on Nrf-2(-/-) mice. Conclusions Leonurine exerted neuroprotective effects, promoted antioxidant responses, and upregulated VEGF expression by activating the Nrf-2 pathway.