Tetramethylpyrazine alleviates oxidative stress-induced nerve injury by promoting mitophagy through miR-144-5p/Panx1 following spinal cord injury.

Background

Ligusticum sinense 'Chuanxiong', a Chinese medicinal herb, has long been used clinically to treat injuries. Its primary active compound, tetramethylpyrazine (TMP), has been demonstrated to mitigate oxidative damage in spinal cord injury (SCI) and is emerging as a potential therapeutic agent. However, translating the broad efficacy of natural compounds such as TMP into effective SCI therapies remains difficult, largely because clearly defined primary targets are lacking. This study aims to elucidate the mechanisms through which TMP improves SCI, providing a foundation for targeted therapeutic approaches.

Method

A rat spinal cord contusion model was employed to investigate therapeutic targets of TMP. Motor function was assessed through behavioral tests, while tissue repair was evaluated by histological analysis. Transcriptome sequencing was utilized to identify key microRNAs and downstream mRNAs. In PC12 cells, an H2O2-induced oxidative stress model and a lentiviral Pannexin 1 (Panx1)-overexpressing stable line were established. Mechanisms were further validated using luciferase assays, dihydroethidium (DHE) and 2,7-dichlorodihydrofluorescein diacetate (DCFH-DA) staining, live/dead staining, Western blot, PCR, transmission electron microscopy, and immunofluorescence.

Results

TMP enhanced motor function and promoted neuronal survival around the lesion site in SCI rats. Transcriptomic analysis identified miR-144-5p as a crucial mediator, which was upregulated post-treatment. miR-144-5p directly downregulates Panx1, thereby enhancing mitophagy. This reduction in oxidative stress, contributed to improved neuronal survival and functional recovery.

Conclusions

TMP enhances mitochondrial autophagy and reduces ROS production following SCI by upregulating miR-144-5p and inhibiting Panx1 expression.