Abstract: BACKGROUND: Repetitive trans-spinal magnetic stimulation (rTSMS) can inhibit inflammatory responses following spinal cord injury. rTSMS applies magnetic field stimulation to the spinal cord region to modulate neuronal excitability and synaptic transmission, thereby promoting plasticity and repair of the nervous system.
OBJECTIVE: To observe the effects of rTSMS on the Toll-like receptor 4 (TLR4)/nuclear factor (NF)-κB/NLRP3 signaling pathway after spinal cord injury and explore its mechanism in promoting motor function recovery.
METHODS: Male C57BL/6J mice, SPF grade, were randomly divided into sham surgery group, spinal cord injury group, and rTSMS group. The latter two groups of mice were anesthetized and the T9 vertebral plate was removed using rongeur forceps to expose the spinal cord, and the spinal cord was clamped using a small aneurysm clip for 20 seconds to establish the spinal cord injury model. Mice in the rTSMS group underwent a 21-day rTSMS intervention starting on day 1 after spinal cord injury. The stimulation lasted 10 minutes per day, 5 days per week with an interval of 2 days. Basso Mouse Scale scores were used to assess motor function recovery in mice after spinal cord injury at 1, 3, 7, 14, and 21 days after spinal cord injury. Western blot was employed to detect the expression of AQP4, apoptotic factors Bax, Bcl-2, CL-Caspase-3, inflammatory factors tumor necrosis factor-α, interferon-γ, interleukin-6, interleukin-4, and the TLR4/NF-κB/NLRP3 signaling pathway related proteins in the injured spinal cord. Oxidative stress assay kit was used to measure the activity of superoxide dismutase, glutathione peroxidase, and malondialdehyde content at the site of spinal cord injury. Immunofluorescence staining was performed to detect the expression of neuronal nuclei (NeuN).
RESULTS AND CONCLUSION: The Basso Mouse Scale score in the rTSMS group was significantly higher than that in the spinal cord injury group (P < 0.05). 
Compared with the spinal cord injury group, the rTSMS group showed a reduction in spinal cord water content. The expression of AQP4 protein, malondialdehyde content, and expression of Bax, Bcl-2, CL-Caspase-3, tumor necrosis factor-α, interferon-γ, interleukin-6, and TLR4/NF-κB/NLRP3 signaling pathway related proteins were all decreased in the rTSMS group, while the activities of superoxide dismutase and glutathione peroxidase, as well as the expression of Bcl-2, interleukin-4, and NeuN, were all increased (P < 0.05). These results suggest that rTSMS downregulates the expression of proteins related to the TLR4/NF-κB/NLRP3 signaling pathway, alleviating symptoms after spinal cord injury such as spinal cord edema, oxidative stress, apoptosis, and inflammation, exerting neuroprotective effects, and thereby promoting the recovery of hindlimb motor function after spinal cord injury.

中国组织工程研究杂志出版内容重点：组织构建；骨细胞；软骨细胞；细胞培养；成纤维细胞；血管内皮细胞；骨质疏松；组织工程

Key words: spinal cord injury, repetitive trans-spinal magnetic stimulation, TLR4/NF-κB/NLRP3 signaling pathway, spinal cord edema, oxidative stress, apoptosis, inflammation, neuroprotection, motor function