Effect of electroacupuncture on E-prostanoid 2 expression in the spinal cord in rats with neuropathic pain

Abstract

ObjectiveTo observe the effect of electroacupuncture (EA) treatment on the expression of E-prostanoid 2 (EP2) in the spinal cord using a rat model of neuropathic pain, and to examine the effect of different acupuncture prescriptions. MethodsRats were randomly divided into six groups: a normal group, model group, sham group, EA 1 group (distal-proximal acupoints), EA 2 group (proximal acupoints), and EA 3 group (distal acupoints). Rats in the EA groups were treated for 20 min, once daily for 7 days. The mechanical withdrawal threshold was evaluated at 1 day preoperatively and at 3, 5, and 7 days postoperatively. At 7 days postoperatively, hematoxylin-eosin (HE) staining was used to investigate spinal morphological changes. Spinal EP2 messenger ribonucleic acid (mRNA) was detected using reverse-transcription polymerase chain reaction. ResultsAfter the EA treatment, the mechanical withdrawal threshold was up-regulated compared with the model group (P < 0.05). The expression of EP2 mRNA was up-regulated in the spinal cord on day 7 after surgery (P < 0.05). EA stimulation tended to down-regulate EP2 mRNA expression compared with the model group (P > 0.05). The EA 1 and EA 2 groups showed a larger treatment effect than the EA 3 group. The HE results showed that EA can improve spinal histomorphology induced by neuropathic pain. ConclusionEA had a strong analgesic and anti-inflammatory effect. The therapeutic effect of EA on the down-regulation of spinal EP2 mRNA expression may be greater when either local acupoints or a distal-proximal combination of acupoints are used than when distal points are used.