Electroacupuncture suppresses spinal nerve ligation-induced neuropathic pain via regulation of synaptic plasticity through upregulation of basic fibroblast growth factor expression.

Abstract

Improving synaptic plasticity is a good way to alleviate neuropathic pain. Electroacupuncture (EA) is currently used worldwide to treat this disease, but its specific mechanisms of action need further investigation. Evidence has suggested that basic fibroblast growth factor (bFGF) plays an important role in promoting nerve regeneration and can promote the expression of vascular endothelial growth factor (VEGF). In this study, we examined the effects of EA on synaptic plasticity and its underlying mechanism. A spinal nerve ligation (SNL) rat model was established. NSC37204 (a specific inhibitor of bFGF) was used to determine the relationship between bFGF and putative EA-mediated improvements in synaptic plasticity. Mechanical withdrawal threshold (MWT) and thermal withdrawal latency (TWL) were assessed to evaluate hyperalgesia in rats with SNL. Tissue morphology was detected by hematoxylin-eosin (HE) and Nissl staining, while neural plasticity and its molecular mechanisms were examined by Western blotting, quantitative real-time polymerase chain reaction (qPCR), dual-label immunohistochemistry and transmission electron microscopy. We found that EA improved synaptic plasticity, consistent with higher levels of expression of bFGF and VEGF. Contrary to the beneficial effects of EA, NSC37204 promoted synaptic reconstruction. Furthermore, EA-induced improvements in the neurobehavioral state and improved synaptic plasticity were blocked by NSC37204, consistent with lower expression levels of bFGF and VEGF. These findings indicate that EA suppresses SNL-induced neuropathic pain by improving synaptic plasticity via upregulation of bFGF expression.