Paeoniflorin Ameliorates Spinal Cord Injury by Controlling Apoptosis and Ferroptosis in H₂O₂-Damaged PC12 Cells

Spinal cord injury (SCI) leads to severe neurological dysfunction. Current therapeutic strategies remain limited, with poor recovery rates. Oxidative stress and ferroptosis are key mechanisms underlying secondary SCI. Paeoniflorin has anti-inflammatory, antioxidant, and neuroprotective properties; however, its role in regulating apoptosis and ferroptosis after SCI remains unclear.

An in vitro SCI model was established by treating PC12 cells with 300 μM H₂O₂ for 24 h, followed by intervention with various concentrations of paeoniflorin. Cell viability was assessed using the 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyl tetrazolium bromide (MTT) assay, apoptosis was analyzed by flow cytometry, lipid reactive oxygen species (ROS) levels were detected by immunofluorescence, and cysteine (Cys), glutathione (GSH), and glutathione peroxidase 4 (GPX4) levels were measured using enzyme-linked immunosorbent assay (ELISA) kits. Western blotting and reverse transcription quantitative polymerase chain reaction (RT-qPCR) were performed to evaluate the expression of sirtuin 3 (SIRT3), B-cell lymphoma-2 (Bcl-2), and BCL2-Associated X (Bax). In addition, the SIRT3-specific inhibitor, 3-TYP, was used to validate the role of SIRT3 in paeoniflorin-mediated protection.

Paeoniflorin increased cell viability; reduced apoptosis; suppressed ROS accumulation; and restored Cys, GSH, and GPX4 levels in a dose-dependent manner. Paeoniflorin significantly upregulated SIRT3 mRNA and protein expression. Co-treatment with 3-TYP attenuated the protective effects of paeoniflorin, indicating that the role of paeoniflorin is mediated through activation of the SIRT3 pathway.

Paeoniflorin exerts significant neuroprotective effects against SCI-induced injury by activating the SIRT3 signaling pathway and regulating apoptosis, oxidative stress, and ferroptosis, offering a novel potential therapeutic target for SCI treatment.