Journal of neuroscience research
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Neuropeptide changes in primary sensory neurons caused by partial nerve injury are likely involved in the development of neuropathic pain. In this study, using immunocytochemistry, we examined neuropeptide Y (NPY) expression in lumbar dorsal root ganglion (DRG) cells of young adult (2-3 months old) and middle-aged (8-10 months old) rats 4 weeks after partial sciatic nerve ligation (PSNL). ⋯ Thus PSNL induces NPY up-regulation in spared as well as injured DRG neurons, both contribute to the increased NPY immunoreactivity in the gracile nucleus in the middle-aged rats. The more dramatic increase of NPY in DRG neurons of middle-aged rats after PSNL shows that the responses to partial nerve injury are age-dependent, that suggests a possible relevance to the higher incidence of neuropathic pain in human middle age.