Structural and molecular alterations of primary afferent fibres in the spinal dorsal horn in vincristine-induced neuropathy in rat.

Vincristine is one of the most common anti-cancer drug therapies administered for the treatment of many types of cancer. Its dose-limiting side effect is the emergence of peripheral neuropathy, resulting in chronic neuropathic pain in many patients. This study sought to understand the mechanisms underlying the development of neuropathic pain by vincristine-induced neurotoxicity. We focused on signs of functional changes and revealed that deep layers of the spinal cord (III-IV) experience increased neuronal activity both in the absence of peripheral stimulation and, as a result of tactile mechanical stimulations. These laminae and superficial laminae I-II were also subject to structural changes as evidenced by an increase in immunoreactivity of Piccolo, a marker of active presynaptic elements. Further investigations performed, using DNA microarray technology, describe a large number of genes differentially expressed in dorsal root ganglions and in the spinal dorsal horn after vincristine treatment. Our study describes an important list of genes differentially regulated by vincristine treatment that will be useful for future studies and brings forward evidence for molecular and anatomical modifications of large diameter sensory neurons terminating in deep dorsal horn laminae, which could participate in the development of tactile allodynia.