Journal of orthopaedic science : official journal of the Japanese Orthopaedic Association
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Recent studies have revealed that the low-affinity nerve growth factor receptor, p75 neurotrophin receptor (p75NTR), is important in inflammatory pain. Moreover, p75NTR immunoreactive sensory nerve and dorsal root ganglion (DRG) neurons have been found to innervate lumbar intervertebral discs. The purpose of the current study was to investigate the effect of p75NTR saporin, a toxin used to destroy p75NTR, on calcitonin gene-related peptide (CGRP), an inflammatory neuropeptide associated with pain, in DRG neurons innervating punctured intervertebral discs in rats. ⋯ Half of the DRG neurons innervating the discs were positive for CGRP in the puncture + saline group. CGRP is important for mediating inflammatory and nerve-injured pain and may be important in discogenic pain. However, p75NTR saporin suppressed CGRP expression in DRG neurons. Therefore, p75NTR may be an important receptor for mediating discogenic pain via CGRP expression.