Transcranial direct current stimulation regulates phenotypic transformation of microglia to relieve neuropathic pain induced by spinal cord injury

Frontiers in Behavioral Neuroscience, 2023 · DOI: 10.3389/fnbeh.2023.1147693 · Published: April 4, 2023

Spinal Cord Injury Neurology Pain Management

Simple Explanation

This study investigates how transcranial direct current stimulation (tDCS) can alleviate neuropathic pain after spinal cord injury (SCI) in rats. Neuropathic pain is a common issue post-SCI, and tDCS is explored as a non-invasive treatment option. The researchers examined the impact of tDCS on inflammatory responses in the brain following SCI. They measured levels of inflammatory and anti-inflammatory cytokines and observed changes in microglia, which are immune cells in the brain. The findings suggest that tDCS can reduce neuropathic pain by modulating the inflammatory environment in the brain. Specifically, tDCS appears to influence the behavior of microglia, shifting them from a pro-inflammatory state to an anti-inflammatory state.

Study Duration

Not specified

Participants

30 female Sprague–Dawley (SD) rats

Evidence Level

Original Research

Key Findings

1
tDCS treatment improved thermal withdrawal threshold and motor function in SCI rats compared to the vehicle group.
2
tDCS reduced the levels of pro-inflammatory cytokines (TNF-α, IL-1β, IL-6) in the cortex, thalamus, midbrain, and medulla of SCI rats.
3
tDCS increased the levels of the anti-inflammatory cytokine IL-10 in the thalamus and promoted the shift of microglia from the M1 to M2 phenotype in VPL, VTA, and PAG regions.

Research Summary

This study aimed to explore the effect of tDCS on neuropathic pain induced by SCI and its underlying mechanism, focusing on the role of microglia and cytokines. The results indicate that tDCS can effectively relieve SCI-induced neuropathic pain by regulating inflammatory and anti-inflammatory cytokines in specific brain regions through the phenotypic transformation of microglia. The findings provide a molecular biological mechanism for the clinical use of tDCS in alleviating SCI-induced neuropathic pain, highlighting its potential as a therapeutic intervention.

Practical Implications

Potential Therapeutic Intervention

tDCS could be a promising non-invasive therapy for managing neuropathic pain in SCI patients, especially those who do not respond well to traditional drug treatments.

Microglia Modulation

The study suggests that targeting microglia and promoting their shift to an anti-inflammatory phenotype (M2) could be a key strategy in pain management after SCI.

Cytokine Regulation

Further research into how tDCS influences cytokine levels in the brain could lead to the development of more targeted therapies for neuropathic pain.

Study Limitations

1
The study was conducted on rats, and further research is needed to confirm these findings in human subjects.
2
The specific mechanisms by which tDCS regulates the phenotypic transformation of microglia require further investigation.
3
The long-term effects of tDCS on neuropathic pain and microglial activity were not assessed in this study.

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