Effect of electroacupuncture at distal-proximal acupoint combinations on spinal interleukin-1 beta in a rat model of neuropathic pain

Objective:Pain from herniated disc is a common type of neuropathic pain.This study investigated whether electroacupuncture (EA) stimulation at distal-proximal combinations of acupoints in the rat model of neuropathic pain modulates spinal interleukin-1 beta (IL-1β) to induce acupuncture analgesia and possibly serve as a pain-relief modality for herniated disc.Methods:A rat model of neuropathic pain was established.Rats were randomly divided into normal,model,sham,EA 1,EA 2,and EA 3 groups.EA 1 rats were needled at bilateral ExB2,BL25,BL40,and BL60 acupoints.EA 2 rats Were needled at bilateral BL40 and BL60.EA 3 rats were needled at bilateral L5 Ex-B2 and BL25.EA stimulation was administered once daily over 7 days.Mechanical withdrawal threshold from noxious mechanical stimulation was measured 1 day preoperatively and at 3,5,and7 days postoperatively.After 7 days of intervention,enzyme-linked immunosorbent assay (ELISA) was used to quantify IL-1β in the spinal cord.Results:Mechanical withdrawal threshold of rats in the model group decreased at 3 days postoperatively when compared with the normal group (P < 0.01),lasting 7 days postoperatively.Mechanical withdrawal thresholds in the EA 1,EA 2,and EA 3 groups were elevated over the model group (P < 0.05;P < 0.01).No obvious differences were found between EA 1,EA 2,and EA 3 groups.ELISA demonstrated an increase in IL-1β in the spinal cord of rats in the model group compared with the normal group (P < 0.01).EA treatment attenuated the increase in spinal IL-1β in the model group.Expression of spinal IL-1β was significantly lower in EA 1,EA 2,and EA 3 groups.Conclusion:EA at distal + proximal acupoints,distal points,as well as proximal points attenuated upregulation of spinal IL-1β,alleviated the extent of neuropathic pain hypersensitivity,and promoted mechanical withdrawal threshold,resulting in EA analgesia.