Ephrin B/EphB in neuropathic pain: Role and molecular mechanisms

Ephrins are protein ligands that act through the tyrosine kinase receptor family, Eph receptors. The role of ephrin/Eph in the critical processes involved in the development of the nervous system, including axon guidance and cell migration, has been well documented. Moreover, studies have shown an upregulation of ephrin B1/EphB1 and ephrin B2/EphB2 in neuropathic pain of different etiology. The activation of the ephrin B/EphB system in the dorsal root ganglion and dorsal horn of the spinal cord may be essential in initiating and maintaining neuropathic pain. Accordingly, it can be proposed that the pharmacological inhibitors of EphB receptors may be potentially employed to manage the manifestations of pain. One of the primary mechanisms involved in ephrin B/EphB-mediated synaptic plasticity includes phosphorylation and activation of NMDA receptors, which may be secondary to activation of different kinases, including MAP kinases (MAPK), protein kinase C (PKC), and Src family kinases (SFK). The other molecular mechanisms may include activation of inflammatory cytokines in the spinal cord, caspase-3, calpain-1, phosphoinositide 3-kinase (PI3K), protein kinase A (PKA), and cAMP Response Element-Binding Protein (CREB). The present review discusses the role and molecular mechanisms involved in ephrin B/EphB-mediated neuropathic pain of different etiology.