TY - JOUR T1 - Sodium Channel Na<sub>v</sub>1.7 Is Essential for Lowering Heat Pain Threshold after Burn Injury JF - The Journal of Neuroscience JO - J. Neurosci. SP - 10819 LP - 10832 DO - 10.1523/JNEUROSCI.0304-12.2012 VL - 32 IS - 32 AU - Shannon D. Shields AU - Xiaoyang Cheng AU - Nurcan Üçeyler AU - Claudia Sommer AU - Sulayman D. Dib-Hajj AU - Stephen G. Waxman Y1 - 2012/08/08 UR - http://www.jneurosci.org/content/32/32/10819.abstract N2 - Marked hypersensitivity to heat and mechanical (pressure) stimuli develop after a burn injury, but the neural mechanisms underlying these effects are poorly understood. In this study, we establish a new mouse model of focal second-degree burn injury to investigate the molecular and cellular basis for burn injury-induced pain. This model features robust injury-induced behavioral effects and tissue-specific altered cytokine profile, but absence of glial activation in spinal dorsal horn. Three voltage-gated sodium channels, Nav1.7, Nav1.8, and Nav1.9, are preferentially expressed in peripheral somatosensory neurons of the dorsal root ganglia (DRGs) and have been implicated in injury-induced neuronal hyperexcitability. Using knock-out mice, we provide evidence that Nav1.7 selectively contributes to burn-induced hypersensitivity to heat, but not mechanical, stimuli. After burn model injury, wild-type mice display increased sensitivity to heat stimuli, and a normally non-noxious warm stimulus induces activity-dependent Fos expression in spinal dorsal horn neurons. Strikingly, both effects are absent in Nav1.7 conditional knock-out (cKO) mice. Furthermore, burn injury increases density and shifts activation of tetrodotoxin-sensitive currents in a hyperpolarized direction, both pro-excitatory properties, in DRG neurons from wild-type but not Nav1.7 cKO mice. We propose that, in sensory neurons damaged by burn injury to the hindpaw, Nav1.7 currents contribute to the hyperexcitability of sensory neurons, their communication with postsynaptic spinal pain pathways, and behavioral thresholds to heat stimuli. Our results offer insights into the molecular and cellular mechanisms of modality-specific pain signaling, and suggest Nav1.7-blocking drugs may be effective in burn patients. ER -