Transcranial direct current stimulation-mediated miR-298-5p downregulation enhances autophagy by targeting LC3 to promote motor recovery after spinal cord injury

Abstract

While transcranial direct current stimulation (tDCS) has been shown to contribute to motor recovery after spinal cord injury (SCI), the underlying mechanisms behind this process remain unclear. In the present study, we sought to explore whether tDCS can inhibit apoptosis, activate autophagy, and promote functional recovery. To achieve this aim, SCI was induced in rats using a modified Allen’s method and managed with tDCS. MicroRNAs responding to tDCS administration were detected using microRNA sequencing and validated using a quantitative real-time polymerase chain reaction. Dual-luciferase reporter analysis and miRNA overexpression were applied to verify the possible mechanisms of tDCS regulation. Stimulation of PC12 cells with hydrogen peroxide (H2O2) to simulate SCI models in vitro allowed for the detection of the effect of miR-298-5p on neuronal apoptosis and autophagy induced by SCI. The findings revealed that miR-298-5p was upregulated after SCI and decreased after tDCS. In vitro, miR-298-5p silencing was found to promote autophagy and reduce apoptosis in SCI, whereas miR-298-5p overexpression was associated with enhanced SCI-induced neuronal injury. LC3 was demonstrated to be the functional target of miR-298-5p, and tDCS was found to enhance autophagy flux, reduce neuronal apoptosis, improve nerve fiber regeneration, and minimize motor deficits after SCI in vivo. However, all tDCS-induced effects were counteracted after overexpression of miR-298-5p by agomir. In conclusion, this study shows that while miR-298-5p could be detrimental to SCI, tDCS can increase autophagy flux and inhibit neuronal apoptosis by negatively regulating miR-98-5p, thereby improving the recovery of motor function in SCI.