Oxysophoridine protects against cerebral ischemia/reperfusion injury via inhibition of TLR4/p38MAPK-mediated ferroptosis

Oxysophoridine (OSR) is an alkaloid extracted from Sophora alopecuroides L. and exerts beneficial effects in cerebral ischemia/reperfusion (I/R) injury. However, the molecular mechanism underlying the regulatory effects of OSR in cerebral I/R injury remains unclear. In the present study, a cerebral I/R injury rat model was established by occlusion of the right middle cerebral artery. Hematoxylin and eosin and triphenyltetrazolium chloride staining were performed to assess histopathological changes and the extent of cerebral injury to the brain. A Cell Counting Kit-8 and TUNEL assay and western blotting were performed to assess cell viability and apoptosis. Ferroptosis and oxidative stress were evaluated based on ATP and Fe(2+) levels and DCFH-DA staining. The protein expression levels of inflammatory factors were assessed using ELISA. The protein expression levels of members of the toll-like receptor (TLR)4/p38MAPK signaling pathway were evaluated using immunofluorescence staining and western blotting. The results demonstrated that OSR decreased brain injury and neuronal apoptosis in the hippocampus in I/R-induced rats. OSR inhibited reactive oxygen species (ROS) production, decreased levels of ATP, Fe(2+) and acyl-CoA synthetase long-chain family member 4 (ACSL4) and transferrin 1 protein and increased the protein expression levels of ferritin 1 and glutathione peroxidase 4. Furthermore, OSR blocked TLR4/p38MAPK signaling in brain tissue in the I/R-induced rat. In vitro experiments demonstrated that TLR4 overexpression induced generation of ROS, ATP and Fe(2+), which promoted the expression of ferroptosis-associated proteins in hippocampal HT22 neuronal cells. The ferroptosis inducer erastin decreased the effects of OSR on oxygen-glucose deprivation/reoxygenation (OGD/R)-induced cell viability, oxidative stress and inflammatory response. Together, the results demonstrated that OSR alleviated cerebral I/R injury via inhibition of TLR4/p38MAPK-mediated ferroptosis.