Catestatin Enhances Neuropathic Pain Mediated by P2X4 Receptor of Dorsal Root Ganglia in a Rat Model of Chronic Constriction Injury.

ABSTRACT

BACKGROUND/AIMS: Neuropathic pain (NPP) is the consequence of a number of central nervous system injuries or diseases. Previous studies have shown that NPP is mediated by P2X4 receptors that are expressed on satellite glial cells (SGCs) of dorsal root ganglia (DRG). Catestatin (CST), a neuroendocrine multifunctional peptide, may be involved in the pathogenesis of NPP. Here, we studied the mechanism through which CST affects NPP. METHODS: We made rat models of chronic constriction injury (CCI) that simulate neuropathic pain. Rat behavioral changes were estimated by measuring the degree of hyperalgesia as assessed by the mechanical withdrawal threshold (MWT) and the thermal withdrawal latency (TWL). P2X4 mRNA expression was detected by quantitative real-time reverse transcription-polymerase chain reaction. P2X4 protein level and related signal pathways were assessed by western blot. Additionally, double-labeled immunofluorescence was employed to visualize the correspondence between the P2X4 receptor and glial fibrillary acidic protein. An enzyme-linked immunosorbent assay was performed to determine the concentration of CST and inflammatory factors. RESULTS: CST led to lower MWT and TWL and increased P2X4 mRNA and protein expression on the SGCs of model rats. Further, CST upregulated the expression of phosphor-p38 and phosphor-ERK 1/2 on the SGCs of CCI rats. However, the expression level of phosphor-JNK and phosphor-p65 did not obviously change. CONCLUSION: Taken together, CST might boost NPP by enhancing the sensitivity of P2X4 receptors in the DRG of rats, which would provide us a novel perspective and research direction to explore new therapeutic targets for NPP.