Paclitaxel in vitro reversibly sensitizes the excitability of IB4(−) and IB4(+) sensory neurons from male and female rats

BACKGROUND AND PURPOSE: Paclitaxel produces a chemotherapy‐induced peripheral neuropathy that persists in 50–60% of cancer patients upon treatment. Evidence from animal models suggests an axonopathy of peripheral A‐ and C‐type fibres that affects their excitability. However, direct effects of paclitaxel on sensory neuron excitability and sexual dimorphism remain poorly understood. EXPERIMENTAL APPROACH: We used a long‐lasting (10 days in vitro) primary culture of rat dorsal root ganglion (DRG) neurons to investigate the time course effect of paclitaxel on the electrical activity of IB4(−) and IB4(+) sensory neurons of female and male adult Wistar rats. KEY RESULTS: Paclitaxel strongly and reversibly stimulated spontaneous activity and augmented action potential tonic firing in IB4(−) and IB4(+) neurons in both sexes, peaking at 48 h post‐treatment and virtually disappearing at 96 h. Paclitaxel decreased the current rheobase for action potential firing by reducing and accelerating the after‐hyperpolarization phase. Molecularly, paclitaxel modulated Na(+) and K(+) ion currents. Particularly, the drug significantly augmented the function of Na(v)1.8, TRPV1 and TRPM8 channels. Furthermore, paclitaxel increased Na(v)1.8 and TRPV1 expression at 48 h post‐treatment. Notably, we observed that female DRG neurons appear more sensitive to paclitaxel sensitization than their male counterparts. CONCLUSIONS AND IMPLICATIONS: Our data indicate that paclitaxel similarly potentiated IB4(−) and IB4(+) electrogenicity and uncover a potential sex dimorphism in paclitaxel‐induced chemotherapy‐induced peripheral neuropathy. Our in vitro, pre‐clinical, chemotherapy‐induced peripheral neuropathy paradigm provides a tool for studying the dynamics and underlying molecular mechanisms contributing to nociceptor sensitization in peripheral neuropathies and for testing desensitizing compounds.