Low-Frequency Electroacupuncture Alleviates Chronic Constrictive Injury-Induced Mechanical Allodynia by Inhibiting NR2B Upregulation in Ipsilateral Spinal Dorsal Horn in Rats

Zhao W, Jiang Z, Shi H, Xu L, Yang Y, Wang Y · Chinese Journal of Integrative Medicine · 2018 November 22

Objective

To investigate the effects of electroacupuncture on pain sensitivity and N-methyl-D-aspartate receptor type 2B expression in the ipsilateral spinal dorsal horn of rats with chronic constrictive injury, and to explore the analgesic mechanisms of electroacupuncture.

Conclusions

Low-frequency electroacupuncture had an antinociceptive effect in the chronic constrictive injury rat model, potentially by inhibiting N-methyl-D-aspartate receptor type 2B expression.

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Insights

Low-frequency electrical acupuncture reduced nerve injury pain in rats by suppressing a spinal cord receptor linked to pain sensitisation.

Rats were randomly assigned to sham surgery, sciatic nerve constriction injury, or electrical acupuncture treatment groups. The injury model was created by loosely tying ligatures around the left sciatic nerve. Treated rats received daily low-frequency electrical stimulation at leg acupuncture points for thirty days. Pain sensitivity was assessed repeatedly using paw withdrawal responses, while lower spinal cord tissue was collected at several time points to measure receptor-producing cells and receptor gene expression. Sciatic nerve injury caused sustained heightened pain sensitivity and increased expression of the N-methyl-D-aspartate receptor type 2B in the spinal dorsal horn. Electrical acupuncture improved paw withdrawal responses after injury and reduced both receptor-positive cells and receptor gene expression, particularly at later stages, suggesting that reduced spinal pain signalling contributed to its analgesic effect.