The c-kit signaling pathway is involved in the development of persistent pain

Abstract 

Protein kinase signal transduction pathways play critical roles in regulating nociception. Here we show that c-kit, a tyrosine kinase receptor, is expressed in lamina I and II layer of the dorsal horn. Moreover, the superficial c-kit⁺ fibers originate from the dorsal root ganglion, and c-kit in lamina II inner layer comes from intrinsic expression of the spinal cord. Kit^W-v mice, which contain a hypomorphic mutation, exhibited normal acute pain in most pain behavior tests. In the formalin test, the first phase was not affected, whereas the second phase pain response of Kit^W-v mice was significantly reduced relative to wild-type littermates. Kit^W-v mice also showed abnormal neuropathic pain, notably in the contralateral side of nerve injury. The expression and release of CGRP and substance P were not altered by the c-kit mutation. Together, these results implicate c-kit-mediated signal transduction in the development of persistent pain.

Keywords: Tyrosine kinase receptor, c-kit, DRG, Spinal cord, Formalin test, CCI, Persistent pain