Neuroscience letters
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Neuroscience letters · Aug 2010
Spinal TRPA1 ion channels contribute to cutaneous neurogenic inflammation in the rat.
In the spinal dorsal horn, TRPA1 ion channels on central terminals of peptidergic primary afferent nerve fibers regulate transmission to glutamatergic and GABAergic interneurons. Here we determine the cutaneous anti-inflammatory effect of a spinally administered TRPA1 channel antagonist to test the hypothesis that spinal TRPA1 channels contribute to cutaneous neurogenic inflammation induced by sustained noxious stimulation. According to the hypothesis, spinal TRPA1 channels facilitate transmission of injury discharge to GABAergic interneurons that induce a dorsal root reflex, which results in increased release of proinflammatory compounds in the skin. ⋯ The capsaicin-induced blood flow increase was attenuated in a dose-related fashion by i.t. pretreatment with CHEM (3-10microg). Pretreatment with CHEM at a dose of 3mg/kg i.p. or 20microg i.pl. failed to attenuate the capsaicin-induced increase of blood flow. The results indicate that spinal TRPA1 channels contribute to cutaneous neurogenic inflammation adjacent to the injury site, probably by facilitating a dorsal root reflex in peptidergic primary afferent nerve fibers.