A role for the TTX-resistant sodium channel Nav 1.8 in NGF-induced hyperalgesia, but not neuropathic pain

The tetrodotoxin-resistant voltage-gated sodium channel Nav 1.8 is expresse d only in nociceptive sensory neurons. This channel has been proposed to co ntribute significantly to the sensitization of primary sensory neurons afte r injury. We have studied the nociceptive behaviours of mice carrying a nul l mutation in the Nav 1.8 gene (Nav 1.8 -/-) in models of peripheral inflam mation as well as a model of neuropathic pain. The results from the present studies reveal that Nav 1.8 is a necessary mediator of NGF-induced thermal hyperalgesia but is not essential for PGE(2)-evoked hypersensitivity. Neur opathic pain behaviours were unchanged in Nav 1.8 -/- mice indicating that this channel is not involved in the alteration of sensory thresholds follow ing peripheral nerve injury. NeuroReport 12:3077-3080 (C) 2001 Lippincott W illiams & Wilkins.