Paclitaxel chemotherapy treatment often leads to neuropathic pain resistant to available analgesic treatments. Recently spinal Toll-like receptor 4 (TLR4) and the transient receptor potential cation channel subfamily V member 1 (TRPV1) were identified to be involved in the pro-nociceptive effect of paclitaxel. The aim of this study was to investigate the role of phosphatidylinositol 3-kinase (PI3K) and serine/threonine kinases in this process, with the use of their antagonists (wortmannin, LY-294002, and staurosporine). The single paclitaxel administration (8 mg/kg i.p.) in mice induced robust mechanical allodynia measured as a reduced threshold to von Frey filament stimulation and generated reduced tachyphylaxis of capsaicin-evoked responses, recorded as changes in mEPSC frequency in patch-clamp recordings of dorsal horn neurons activity in vitro, for up to eight days. Paclitaxel application also induced increased Akt kinase phosphorylation in rat DRG neurons. All these paclitaxel-induced changes were prevented by the wortmannin in vivo pretreatment. Acute co-application of wortmannin or LY-294002 with paclitaxel in spinal cord slices also attenuated the paclitaxel effect on capsaicin-evoked responses. Staurosporine was effective in the acute in vitro experiments and on the first day after the paclitaxel treatment in vivo, but in contrast to wortmannin, it did not have a significant impact later. Our data suggest that the inhibition of PI3K signaling may help alleviate pathological pain syndromes in the paclitaxel-induced neuropathy.

Department of Functional Morphology Institute of Physiology of the Czech Academy of Sciences Videnska 1083 Prague 14220 Czech Republic

Department of Physiology Faculty of Science Charles University Prague Vinicna 7 Prague 128 44 Czech Republic

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