Effects of electroacupuncture on expression of somatostatin and preprosomatostatin mRNA in dorsal root ganglions and spinal dorsal horn in neuropathic pain rats

Somatostatin (SOM) is an endogenous non-opioid neuropeptide that has analgesic effect in rodents and human beings. Previous studies indicated that SOM might be involved in the modulating effects of electroacupuncture (EA). Using immunohistochemistry and RT-PCR, the present study observed the effects of EA on the expression of SOM peptide and preprosomatostatin (ppSOM) mRNA in a rat model of neuropathic pain induced by chronic constriction injury (CCI) to the sciatic nerve. No significant change was detected in the expression of SOM and ppSOM mRNA following CCI. However, EA could significantly enhance SOM expression in dorsal root ganglion (DRG) and spinal dorsal horn as well as ppSOM mRNA level in DRG of neuropathic pain rats. The present data demonstrated that EA could activate endogenous SOM of neuropathic pain rats and this might be one of the mechanisms that underlie the effectiveness of EA in the treatment of neuropathic pain.