Background: Systemic administration of oxaliplatin has no effect on the tumors in the central nervous system (CNS) due to the limited concentration of oxaliplatin in the cerebrospinal fluid (CSF), while it was clinically reported that oxaliplatin can induce acute encephalopathy. Currently, the impairment of neuronal functions in the CNS after systemic administration of oxaliplatin remains uninvestigated.
Methods: The von Frey test and the plantar test were performed to evaluate neuropathic pain behavior after a single intraperitoneal administration of oxaliplatin (4 mg/kg) in rats. Inductively coupled plasma-mass spectrometry, electrophysiologic recording, real-time quantitative reverse transcription polymerase chain reaction, chromatin immunoprecipitation, Western blot, immunohistochemistry, and small interfering RNA were applied to understand the mechanisms.
Results: Concentration of oxaliplatin in CSF showed a time-dependent increase after a single administration of oxaliplatin. Spinal application of oxaliplatin at the detected concentration (6.6 nM) significantly increased the field potentials in the dorsal horn, induced acute mechanical allodynia (n = 12 each) and thermal hyperalgesia (n = 12 each), and enhanced the evoked excitatory postsynaptic currents and spontaneous excitatory postsynaptic currents in the projection neurokinin 1 receptor-expressing lamina I to II neurons. The authors further found that oxaliplatin significantly increased the nuclear factor-κB p65 binding and histone H4 acetylation in cx3cl1 promoter region. Thus, the upregulated spinal CX3CL1 markedly mediated the induction of central sensitization and acute pain behavior after oxaliplatin administration.
Conclusions: The findings of this study suggested that oxaliplatin in CSF may directly impair the normal function of central neurons and contribute to the rapid development of CNS-related side effects during chemotherapy. This provides novel targets to prevent oxaliplatin-induced acute painful neuropathy and encephalopathy.