Pain Mediation By Innocuous Sensory Afferents

Main Category: Pain / Anesthetics
Also Included In: Neurology / Neuroscience
Article Date: 06 Aug 2008 - 5:00 PDT

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Expression of protein kinase Cγ (PKCγ) in interneurons of lamina II of the spinal cord dorsal horn is thought to be essential for mechanical allodynia, a painful response to normally innocuous stimuli. Nonpeptidergic nociceptors were initially assumed to innervate PKCγ interneurons, because they terminate in the same sublamina.

Neumann et al. now show that the terminals of nonpeptidergic nociceptor afferents terminate dorsal to the PKCγ interneurons, with only minimal overlap. In contrast, the terminals of medium- and large-diameter myelinated afferents overlapped extensively with PKCγ neurons, and electron microscopy showed direct synapses between terminals of largediameter, myelinated afferents and PKCγ interneurons.

Moreover, innocuous stimulation walking on a rotarod) increased Fos expression in PKCγ interneurons, whereas painful stimuli did not. Therefore, a normally innocuous pathway appears to mediate allodynic pain. But the modality of sensory information carried by the afferents that innervate the PKCγ interneurons remains unknown.

Journal of Neuroscience

The Journal of Neuroscience is the official journal of the Society for Neuroscience. The Journal publishes papers on a broad range of topics of general interest to those working on the nervous system.

Journal of Neuroscience