Nadolol Attenuates Brain Cell Ferroptosis in Ischemic Stroke Rats by Targeting the HOIL-1/IRP2 Pathway

Introduction: Heme-oxidized iron regulatory protein 2 (IRP2) ubiquitin ligase-1 (HOIL-1) is believed to contribute to the ubiquitination of IRP2, which facilitates the transcription of transferrin receptor 1 (TfR1) while preventing the transcription of ferroportin-1 (FPN-1). Bioinformatics analysis predicts that nadolol (a β-blocker) interacts with the HOIL-1.

Method: The present study is intended to explore whether nadolol suppresses ferroptosis in the brains of rats suffering from ischemic stroke via targeting the HOIL-1/IRP2 pathway. A rat model of ischemic stroke was established by blocking the middle cerebral artery for 2 h plus 24 h reperfusion, and nadolol (2.5 or 5 mg/kg) was given at 1h after reperfusion. HT22 cells were subjected to 12 h of hypoxia, followed by 24 h of reoxygenation for simulating ischemic stroke, and nadolol (0.1 or 0.25 μM) was administered to the culture medium before reoxygenation.

Results: The stroke rats showed evident brain injury (increases in neurological deficit score and infarct volume) and ferroptosis, along with up-regulation of IRP2 and TfR1 while downregulation of HOIL-1 and FPN-1; these phenomena were reversed in the presence of nadolol. In the cultured HT22 cells, hypoxia/reoxygenation-induced LDH release, ferroptosis, and changes in the levels of relevant proteins (IRP2, TfR1, HOIL-1, and FPN-1) were also reversed by nadolol.

Conclusion: In terms of these findings, it is concluded that nadolol can protect the ischemic rats' brains against ferroptosis by targeting the HOIL-1/IRP2 pathway, thereby preventing intracellular iron overload. Thus, nadolol may be a novel indication for treating patients with ischemic stroke.