Effect of electroacupuncture on interleukin-6 and procalcitonin expression in the astrocytes and neurons of the spinal cord dorsal horn in a rat model of incisional pain.

Objective: Incisional pain, which is the most commonly observed postoperative complication, is closely related to the release of inflammatory mediators and cytokines. Although electroacupuncture (EA) has been demonstrated to reduce incisional pain, its analgesic mechanisms remain unclear. We aimed to investigate whether EA alleviates incisional pain in rats by regulating the expression of interleukin (IL)-6 and procalcitonin (PCT) in the astrocytes and neurons of the spinal cord dorsal horn.

Methods: Forty-six healthy male Sprague-Dawley rats were included, of which n = 8 were assigned to the control group. The remaining 38 rats were used to establish the incisional pain model. Finally, 32 successfully modeled rats were obtained and randomly divided into model, sham EA, 2 Hz and 20/100 Hz EA groups. Mechanical pain withdrawal threshold (MPWT) was measured before modeling, 6 h after modeling, and 3 days after EA intervention. Enzyme-linked immunosorbent assay, Western blotting and immunofluorescence were used to detect IL-6 and PCT protein and mRNA expression, as well as their co-expression with glial fibrillary acidic protein (GFAP, a marker of astrocytes) and NeUN (a marker of neurons) in the spinal dorsal horn of rats in each group after 3 days of EA intervention.

Results: Reduced IL-6 and PCT levels in the astrocytes and neurons were observed in the spinal dorsal horn of the incisional pain model after EA intervention, and incisional pain was also significantly relieved.

Conclusion: Both 2 Hz and 20/100 Hz EA appear to relieve incisional pain in rats and these effects may be related to inhibition of IL-6 and PCT expression in the spinal dorsal horn.