Oxaliplatin evokes P2X7-dependent glutamate release in the cerebral cortex: A pain mechanism mediated by Pannexin 1

Anticancer therapy based on the repeated administration of oxaliplatin is limited by the development of a neuropathic syndrome difficult to treat. Oxaliplatin neurotoxicity is based on complex nervous mechanisms, the comprehension of the role of single neurotransmitters and the knowledge of the signal flow among cells is matter of importance to improve therapeutic chances. In a rat model of oxaliplatin-induced neuropathy, we report increased P2X7-evoked glutamate release from cerebrocortical synaptosomes. The release was abolished by the P2X7 receptor (P2X7R) antagonists Brilliant-Blue-G (BBG) and A-438079, and significantly reduced by Carbenoxolone and the Pannexin 1 (Panx1) selective inhibitors Erioglaucine and (10)Panx suggesting the recruitment of Panx1. Aimed to evaluate the significance of P2X7R-Panx1 system activation in pain generated by oxaliplatin, pharmacological modulators were spinally infused by intrathecal catheter in oxaliplatin-treated animals. BBG, Erioglaucine and (10)Panx reverted oxaliplatin-dependent pain. Finally, the influence of the P2X7R-Panx1 system blockade on oxaliplatin anticancer activity was evaluated on the human colon cancer cell line HT-29. Prevention of HT-29 apoptosis and mortality was dependent by kind and concentration of P2X7R antagonists. On the contrary, the inhibition of Panx1 did not alter oxaliplatin lethality in tumor cells. It is concluded that glutamate release dependent on P2X7R is increased in cerebrocortical nerve terminals from oxaliplatin-treated rats; the increase is mediated by functional recruitment of Panx1; P2X7R antagonists and Panx1 inhibitors revert oxaliplatin-induced neuropathic pain; Panx1 inhibitors do not alter the oxaliplatin-induced mortality of cancer cells HT-29. The inhibition of Panx1 channel is suggested as a new and safe pharmacological target.