Oxaliplatin elicits mechanical and cold allodynia in rodents via TRPA1 receptor stimulation

Platinum-based anticancer drugs cause neurotoxicity. In particular, oxaliplatin produces early-developing, painful, and cold-exacerbated paresthesias. However, the mechanism underlying these bothersome and dose-limiting adverse effects is unknown. We hypothesized that the transient receptor potential ankyrin 1 (TRPA1), a cation channel activated by oxidative stress and cold temperature, contributes to mechanical and cold hypersensitivity caused by oxaliplatin and cisplatin. Oxaliplatin and cisplatin evoked glutathione-sensitive relaxation, mediated by TRPA1 stimulation and the release of calcitonin gene-related peptide from sensory nerve terminals in isolated guinea pig pulmonary arteries. No calcium response was observed in cultured mouse dorsal root ganglion neurons or in naïve Chinese hamster ovary (CHO) cells exposed to oxaliplatin or cisplatin. However, oxaliplatin, and with lower potency, cisplatin, evoked a glutathione-sensitive calcium response in CHO cells expressing mouse TRPA1. One single administration of oxaliplatin produced mechanical and cold hyperalgesia in rats, an effect selectively abated by the TRPA1 antagonist HC-030031. Oxaliplatin administration caused mechanical and cold allodynia in mice. Both responses were absent in TRPA1-deficient mice. Administration of cisplatin evoked mechanical allodynia, an effect that was reduced in TRPA1-deficient mice. TRPA1 is therefore required for oxaliplatin-evoked mechanical and cold hypersensitivity, and contributes to cisplatin-evoked mechanical allodynia. Channel activation is most likely caused by glutathione-sensitive molecules, including reactive oxygen species and their byproducts, which are generated after tissue exposure to platinum-based drugs from cells surrounding nociceptive nerve terminals.