Brain research
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Comparative Study
P2X3-immunoreactive primary sensory neurons innervating lumbar intervertebral disc in rats.
The P2X(3) receptor is normally localized in a sub-population of small-diameter dorsal root ganglion (DRG) neurons, and is thought to be related to pain perception. The aim of this study in rats was to examine P2X(3)-immunoreactivity in DRG neurons innervating the lumbar disc and in DRG neurons innervating cutaneous tissues. Fluoro-Gold was applied to the L5-L6 disc, the plantar skin of the hind paw (L4-L5 dermatomes), and the back skin (L1-L2 dermatomes). ⋯ The proportion of P2X(3)-immunoreactive neurons was significantly larger in the DRG neurons innervating the plantar or the back skin, than in the DRG neurons innervating the lumbar disc. These results suggest that the P2X(3) receptors are abundant in DRG neurons innervating cutaneous tissues, but not in neurons innervating the lumbar disc. It is likely therefore that the P2X(3) receptor is less related to the mechanism of discogenic pain, than to cutaneous tissue pain.