Effects of repetitive transcranial magnetic stimulation on apoptosis and MAPK/PI3K-AKT signaling pathways in rats with spinal cord injury.

Abstract

BACKGROUND: Repetitive transcranial magnetic stimulation (rTMS) is a promising non-invasive neuromodulation technique, but its mechanisms in spinal cord injury (SCI) remain unclear. This study investigated the effects and potential mechanisms of rTMS on motor recovery in SCI rats. METHODS: A rat SCI model was established using the modified Allen's method. rTMS treatment was initiated on postoperative Day 2 and administered daily for 56 days. Bioinformatics analysis was first conducted to identify SCI-related genes and signaling pathways. Western blotting, immunofluorescence staining, TUNEL assay, NeuN staining, motor evoked potential (MEP) measurement, hematoxylin-eosin staining, and Basso-Beattie-Bresnahan (BBB) score were performed to evaluate molecular and functional outcomes. RESULTS: Bioinformatics analysis identifies MAPK-, PI3K/AKT-, and Bcl-2-related genes as potentially involved in SCI pathology. Western blotting reveals that rTMS is associated with lower levels of p-JNK, p-p38 MAPK, Bax, and caspase-3, and with higher levels of p-ERK, p-PI3K, p-AKT, and Bcl-2 (P&#x202f;<&#x202f;0.001). Immuno&#xfb02;uorescence staining shows that rTMS is accompanied by reduced p-JNK and p-p38 MAPK positive cells and increased p-ERK, p-PI3K and p-AKT positive cells (P&#x202f;<&#x202f;0.001). TUNEL and NeuN staining further suggest reduced neuronal apoptosis in the injured spinal cord. Behavioral and electrophysiological assessments show that rTMS is associated with shorter MEP latencies, higher MEP amplitudes, reduced spinal tissue damage, attenuated muscle atrophy, and improved BBB score (P&#x202f;<&#x202f;0.001). CONCLUSION: rTMS is associated with improvements in motor function and anti-apoptotic molecular changes in SCI rats, possibly via modulation of MAPK and PI3K/AKT signaling pathways, including upregulation of Bcl-2 and downregulation of Bax and caspase-3.