Transcranial direct current stimulation promotes post-SCI motor recovery via miR-298-5p/ LC3-dependent autophagy activation

While transcranial direct current stimulation (tDCS) has been shown to contribute to motor recovery after spinal cord injury (SCI), the mechanisms remain unclear. This study investigated whether tDCS exerts neuroprotective effects by regulating apoptosis and autophagy. To achieve this aim, SCI was induced in rats using a modified Allen's method with tDCS treatment. Otherwise,Furthermore, tDCS-responsive miRNAs were detected by using microRNA (miRNA) sequencing and validated via RT-qPCR. Similarly, tDCS regulatory mechanisms were verified through dual-luciferase assays and miRNA overexpression. Subsequently, H2O2-treated PC-12 cells simulated SCI in vitro to examine miR-298-5p's effects on apoptosis and autophagy. The findings revealed that miR-298-5p was upregulated post-SCI and downregulated after tDCS. In vitro, miR-298-5p silencing promoted autophagy and reduced apoptosis, whereas overexpression exacerbated neuronal injury. LC3 was a direct of miR-298-5p, and tDCS enhanced autophagy, reduced apoptosis, improved nerve regeneration, and minimized motor deficits after SCI. Notably, all tDCS-induced effects were counteracted after the overexpression of miR-298-5p by agomir. In summary, this study showed that while miR-298-5p could be detrimental to SCI, tDCS could increase autophagy flux and inhibit neuronal apoptosis by negatively regulating miR-298-5p, thereby improving the recovery of function in SCI. Overall design: The experiment utilized a randomized controlled design with two parallel groups: control group (SCI-1, SCI-2, SCI-3) and experimental group (tDCS-1, tDCS-2, tDCS-3), each comprising three biological replicates (n=3 per group). Samples were randomly assigned to either group to ensure balanced allocation. This design aligns with standard protocols for interventional comparisons, where the experimental group receives transcranial direct current stimulation (tDCS) treatment, while the control group undergoes placebo procedures. Both groups were analyzed under identical conditions to minimize confounding variables