Transcranial magnetic stimulation through attenuating blood-spinal cord barrier disruption and reducing inflammatory response to improve motor function in rats with spinal cord injury.

BACKGROUND

Previous therapies for spinal cord injury (SCI) typically focus on the lesion site, neglecting the interconnected brain areas. Transcranial magnetic stimulation (TMS) is an emerging non-invasive neuromodulation technique, demonstrating potential in modulating the primary motor cortex to enhance SCI recovery.

METHODS

The modified Allen's method was used to establish an SCI rat model. High-frequency repetitive TMS (HF-rTMS) intervention was initiated on the second day after modeling and continued for 56 days. Bioinformatics analysis identified key genes involved in the SCI pathological process, including MMP9, IL-1β, and IL-18. This study explored the functions and mechanisms of these genes in HF-rTMS-mediated motor recovery in SCI rats.

RESULTS

Western blotting reveals that HF-rTMS decreases active-MMP9/pro-MMP9, TNF-α, IL-1β, and IL-18 proteins' expression, while increases β-DG, Occludin, Claudin-5, and ZO-1 proteins' expression in injured spinal cord (P < 0.001). Immunofluorescence staining further shows that HF-rTMS reduces MMP9 positive cells, while enhances Occludin, Claudin-5, and ZO-1 positive cells (P < 0.001). Evans Blue staining indicates that HF-rTMS reduces blood-spinal cord barrier (BSCB) permeability following injury, while ELISA results demonstrate that HF-rTMS attenuates serum levels of pro-inflammatory cytokines. Motor-evoked potentials (MEP) assessment, HE staining, and BBB score show that HF-rTMS shortens MEP latency, enhances MEP amplitude, reduces spinal cord damage and improves motor function (P < 0.001).

CONCLUSION

These findings reveal that HF-rTMS may be associated with suppressing MMP9 activation, protecting tight junction proteins, diminishing basement membrane destruction, and maintaining BSCB integrity. Simultaneously, it may alleviate pro-inflammatory cytokine-induced inflammation, thereby reducing spinal cord tissue damage and promoting motor recovery after SCI.