Sympathetic axons surround neuropeptide-negative axotomized sensory neurons.
Nerve injury can lead to sympathetically dependent neuropathic pain. A possible site of sympathetic-sensory interaction is the dorsal root ganglion (DRG), where sympathetic axons form pericellular 'baskets' around a subpopulation of DRG neurons. Since these structures possibly represent functional units of sympathetic pain, we attempted to characterize the neuropeptidergic phenotype of basketed DRG neurons. We performed double-labeling immunohistochemistry for tyrosine hydroxylase and neuropeptides on DRG sections, 2 weeks following L5 spinal nerve ligation (a well-characterized animal model of sympathetic pain). We found that basketed DRG neurons typically do not contain substance P, calcitonin gene-related peptide, galanin, neuropeptide tyrosine, or vasoactive intestinal polypeptide, and we conclude that if sympathetic baskets contribute to neuropathic pain, the involvement of these neuropeptides is unimportant.
Ramer
M S
MS
Department of Physiology, Queen's University, Kingston, ON, Canada.
Bisby
M A
MA
D000818:Animals; D001369:Axons / Q000502:physiology*; D019771:Axotomy; D015740:Calcitonin Gene-Related Peptide / Q000032:analysis; D019004:Galanin / Q000032:analysis; D005727:Ganglia, Spinal / Q000473:pathology; D007150:Immunohistochemistry; D008026:Ligation; D009475:Neurons, Afferent / Q000473:pathology*; D009478:Neuropeptide Y / Q000032:analysis; D009479:Neuropeptides / Q000032:analysis / Q000172:deficiency*; D051381:Rats; D013127:Spinal Nerves / Q000293:injuries; D013373:Substance P / Q000032:analysis; D013564:Sympathetic Nervous System / Q000166:cytology* / Q000502:physiology*; D014446:Tyrosine 3-Monooxygenase / Q000032:analysis; D014660:Vasoactive Intestinal Peptide / Q000032:analysis
D009478:Neuropeptide Y; D009479:Neuropeptides; D013373:Substance P; D014660:Vasoactive Intestinal Peptide; D019004:Galanin; D014446:Tyrosine 3-Monooxygenase; D015740:Calcitonin Gene-Related Peptide