The effects of low-frequency electroacupuncture on hyperalgesia PKA-TRPV1 signal pathway and neurotransmitters in the spinal cord of rats with neuropathic pain induced by spared nerve injury / 中华物理医学与康复杂志

ABSTRACT

Objective To explore the effect of low-frequency electroacupuncture (EA) on neuropathic pain induced by spinal nerve injury and its underlying mechanism.Methods Thirty-two male Sprague-Dawley rats were randomly divided into a normal group,a sham spared nerve injury (SNI) group,an SNI group and an SNI+EA group,each of 8.The rats in the SNI and SNI+EA groups were given SNI surgery,while those of the sham-SNI group only had the sciatic nerve and its branches exposed without any lesion.EA at 2 Hz was applied over the ipsilateral Zusanli and Kunlun acupoints daily for 14 days after the surgery.The ipsilateral paw withdrawal threshold (PWT) was measured,along with protein kinase A (PKA) levels in the dorsal horn of the spinal cord,calcitonin gene-related peptide (CGRP) and substance P (SP) levels along with transient receptor potential V1 (TRPV1).Results Compared to the normal group,the SNI groups all showed significant decreases in their PWTs on the affected side and significant increases in PKA,TRPV1,CGRP and substance P on the affected side.Compared to SNI group,the average ipsilateral PWT in the SNI+EA group increased significantly after EA treatment,while PKA levels,TRPV1,CGRP levels and SP expression all decreased significantly.Conclusion Electroacupuncture at low frequency can effectively relieve neuropathic pain,perhaps through down-regulation of PKA in the spinal cord and by decreasing pain hypersensitivity related to CGRP and SP.