High-frequency repetitive transcranial magnetic stimulation promotes motor recovery after spinal cord injury associated with spinal-cortical plasticity.

Spinal cord injury (SCI) leads to persistent motor deficits, and effective strategies to enhance neural repair remain limited. Repetitive transcranial magnetic stimulation (rTMS) has been reported to promote neuroplasticity, but its effects on corticospinal remodeling after SCI are not fully understood. In this study, adult female rats were assigned to Sham, SCI, or rTMS groups. High-frequency rTMS was applied daily for 28 days starting 1 day after injury. Motor function was assessed using Basso-Beattie-Bresnahan scoring and gait analysis. Corticospinal conduction was evaluated by motor evoked potentials (MEPs). Histological changes, plasticity-related proteins, and MEK/ERK signaling were examined in the spinal cord and primary motor cortex (M1). Corticospinal tract (CST) remodeling was evaluated using anterograde tracing. rTMS significantly improved locomotor recovery and gait coordination, enhanced MEP responses, and reduced tissue damage compared with SCI controls. These functional improvements were accompanied by increased CST projections distal to the lesion. rTMS also increased phosphorylation of MEK and ERK, together with partial restoration of GAP-43, SYN1, and PSD-95 expression in both spinal cord and M1. These findings indicate that high-frequency rTMS facilitates functional recovery after SCI, which is accompanied by enhanced corticospinal remodeling and plasticity-related signaling.