Innocuous, Not Noxious, Input Activates PKCγ Interneurons of the Spinal Dorsal Horn via Myelinated Afferent Fibers

• DOI: 10.1523/jneurosci.1259-08.2008
• Publication Date: 2008-08-06T16:28:30Z
• Authors: Simona Neumann; Joao M. Braz; Kate Skinner; Ida J. Llewellyn-...; Allan I. Basbaum
• Keywords: Nociceptor; Interneuron; Allodynia

Protein kinase C γ (PKCγ), which is concentrated in interneurons of the inner part lamina II dorsal horn, has been implicated injury-induced allodynia, a condition wherein pain produced by innocuous stimuli. Although it generally assumed that these receive input from nonpeptidergic, IB4-positive subset nociceptors, fact PKCγ cells do not express Fos response to noxious stimulation suggests otherwise. Here, we demonstrate terminal field nonpeptidergic population fact, lies interneurons. There was also no overlap between PKCγ-expressing and transganglionic tracer wheat germ agglutinin which, after sciatic nerve injection, labels all unmyelinated nociceptors. However, transport β-subunit cholera toxin, marks medium-diameter large-diameter myelinated afferents transmit non-noxious information, revealed extensive with layer Furthermore, expression transneuronal resulted labeling Light electron microscopic double further showed VGLUT1 subtype vesicular glutamate transmitter, expressed afferents, synapses are presynaptic Finally, continuous input, generated walking on rotarod, induces These results establish activated respond stimuli, mechanical allodynia transmitted through circuit involves non-nociceptive, VGLUT1-expressing primary afferents.