Anti-inflammatory effects of sacral nerve stimulation: a novel spinal afferent and vagal efferent pathway.

BACKGROUND & AIMS: Sacral nerve stimulation (SNS) was reported to improve TNBS-induced colitis in rats. The aim of this study was to investigate whether the SNS anti-inflammatory effect is mediated via the local sacral splanchnic nerve or the spinal afferent-vagal efferent-colon pathway.

METHODS: Under general anesthesia, rats were administrated with TNBS intra-rectally and bipolar SNS electrodes were implanted unilaterally at S3. The sacral and vagal nerves were severed at different locations for the assessment of the neural pathway.

RESULTS: SNS for 10 days improved colonic inflammation only in groups with intact afferent sacral nerve and vagus efferent nerve. SNS markedly increased acetylcholine and anti-inflammatory cytokines (IL-10), and decreased myeloperoxidase and pro-inflammatory cytokines (IL-2, IL-17A and TNFα) in colon tissues. SNS increased the number of c-fos positive cells in the brain stem and normalized vagal activity measured by spectral analysis of heart rate variability.

CONCLUSIONS: SNS exerts an anti-inflammatory effect on TNBS-induced colitis by enhancing vagal activity mediated mainly via the spinal afferent-brain stem-vagal efferent-colon pathway.