DL-3-n-butylphthalide Attenuates Cerebral Ischemia-Reperfusion Injury by Inhibiting Mitochondrial Omi/HtrA2-Mediated Apoptosis

Background: Ischemic stroke is a major cause of death and disability worldwide and results from inadequate cerebrovascular blood supply; mitochondrial dysfunction plays an essential role in its pathogenesis. DL-3-n-butylphthalide (NBP) is an effective medicine for ischemic stroke that reduces cell apoptosis and improves long-term prognosis. Objective: Whether and how NBP regulates mitochondria-associated apoptosis in cerebral ischemia- reperfusion injury remains unclear. Methods: Male Sprague Dawley rats were subjected to a middle cerebral artery occlusion (MCAO) stroke and treated with low (20 mg/kg) or high (80 mg/kg) concentrations of NBP. The Omi/HtrA2 inhibitor UCF-101 was used as a positive control. Cerebral infarction, neuron injury and neuronal apoptosis were assessed to determine the efficacy of NBP compared to UCF-101. We assessed the expression of the Omi/HtrA2 signaling pathway by western blotting and tested the mRNA expression of mitochondrial metabolism-related genes by PCR. Results: Compared to the MCAO group, both low and high concentrations of NBP substantially improved cerebral infarction, neuron injury, and neuronal apoptosis; high concentrations of NBP were more potent than low concentrations. The expression of proteins of the mitochondrial Omi/HtrA2 signaling pathway, including Omi/HtrA2, XIAP, PARL, OPA1, CHOP, and ClpP, was inhibited in the NBP group. Conclusion: Overall, early application of NBP attenuated cerebral ischemia-reperfusion injury by inhibiting mitochondrial Omi/HtrA2-mediated apoptosis in rats. Our study supports a novel neuroprotective mechanism of NBP, making it a promising therapeutic agent for ischemic stroke.