SDF1–CXCR4 signaling contributes to persistent pain and hypersensitivity via regulating excitability of primary nociceptive neurons: involvement of ERK-dependent Nav1.8 up-regulationReport as inadecuate

SDF1–CXCR4 signaling contributes to persistent pain and hypersensitivity via regulating excitability of primary nociceptive neurons: involvement of ERK-dependent Nav1.8 up-regulation - Download this document for free, or read online. Document in PDF available to download.

Journal of Neuroinflammation

, 12:219

First Online: 24 November 2015Received: 10 July 2015Accepted: 18 November 2015


BackgroundPain is one critical hallmark of inflammatory responses. A large number of studies have demonstrated that stromal cell-derived factor 1 SDF1, also named as CXCL12 and its cognate receptor C-X-C chemokine receptor type 4 CXCR4 play an important role in immune reaction and inflammatory processes. However, whether and how SDF1–CXCR4 signaling is involved in inflammatory pain remains unclear.

MethodsUnder the intraplantar bee venom BV injection-induced persistent inflammatory pain state, the changes of SDF1 and CXCR4 expression and cellular localization in the rat dorsal root ganglion DRG were detected by immunofluorescent staining. The role of SDF1 and CXCR4 in the hyperexcitability of primary nociceptor neurons was assessed by electrophysiological recording. Western blot analysis was used to quantify the DRG Nav1.8 and phosphorylation of ERK pERK expression. Behavioral tests were conducted to evaluate the roles of CXCR4 as well as extracellular signal-regulated kinase ERK and Nav1.8 in the BV-induced persistent pain and hypersensitivity.

ResultsWe showed that both SDF1 and CXCR4 were dramatically up-regulated in the DRG in BV-induced inflammatory pain model. Double immunofluorescent staining showed that CXCR4 was localized in all sizes large, medium, and small of DRG neuronal soma, while SDF1 was exclusively expressed in satellite glial cells SGCs. Electrophysiological recording showed that bath application with AMD3100, a potent and selective CXCR4 inhibitor, could reverse the hyperexcitability of medium- and small-sized DRG neurons harvested from rats following BV injection. Furthermore, we demonstrated that the BV-induced ERK activation and Nav1.8 up-regulation in the DRG could be blocked by pre-antagonism against CXCR4 in the periphery with AMD3100 as well as by blockade of ERK activation by intrathecal i.t. or intraplantar U0126. At behavioral level, the BV-induced persistent spontaneous pain as well as primary mechanical and thermal hypersensitivity could also be significantly suppressed by blocking CXCR4 and Nav1.8 in the periphery as well as by inhibition of ERK activation at the DRG level.

ConclusionsThe present results suggest that peripheral inflammatory pain state can trigger over release of SDF1 from the activated SGCs in the DRG by which SGC-neuronal cross-talk is mediated by SDF1–CXCR4 coupling that result in subsequent ERK-dependent Nav1.8 up-regulation, leading to hyperexcitability of tonic type of the primary nociceptor cells and development and maintenance of persistent spontaneous pain and hypersensitivity.

KeywordsInflammatory pain Chemokines SDF1 CXCR4 Nav1.8 Dorsal root ganglion ERK signaling Fei Yang and Wei Sun contributed equally to this work.

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Author: Fei Yang - Wei Sun - Yan Yang - Yan Wang - Chun-Li Li - Han Fu - Xiao-Liang Wang - Fan Yang - Ting He - Jun Chen



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