title: No overlap of sensitivity to capsaicin and expression of galanin in rat dorsal root ganglion neurons after axotomy.
abstract: The neuropeptide galanin is known to have an antinociceptive effect under neuropathic conditions. After axotomy, galanin is upregulated in sensory neurons, presumably in the capsaicin-sensitive ones. Here, the sensitivity to capsaicin and the expression of galanin were simultaneously examined by double-staining in individual, dissociated rat dorsal root ganglion neurons (1) after axotomy of the sciatic nerve for up to 14 days and (2) in culture for up to 4 days without prior nerve injury. Ten days after axotomy, the proportion of capsaicin-sensitive neurons had decreased by 36 percentage points (from 63% to 27%), whereas the proportion of galaninergic neurons had increased by 33 percentage points (from 3% to 36%). These changes were also observed in neurons kept in culture, where the regulation was attenuated by the addition of nerve growth factor (NGF) or glial cell line-derived neurotrophic factor (GDNF) to the medium. After axotomy, galaninergic neurons had a soma size-distribution profile similar to the capsaicin-sensitive neurons, but there was no colocalization of capsaicin sensitivity and galanin expression in individual neurons. In culture, some neurons showed colocalization after 30 h and 48 h, but not after 6 h or 96 h. We conclude that the upregulation of galanin in an individual neuron is preceded by downregulation of its capsaicin sensitivity both in NGF-dependent peptidergic and in GDNF-dependent non-peptidergic neurons, indicating a change in phenotype.
authors.affiliation: Department of Physiology, University of Würzburg, Roentgenring 9, 97070 Würzburg, Germany.
authors.forename: Jens R
authors.initials: JR
authors.lastname: Wendland
authors.forename: Klaus H
authors.initials: KH
authors.lastname: Schmidt
authors.forename: Martin
authors.initials: M
authors.lastname: Koltzenburg
authors.forename: Marlen
authors.initials: M
authors.lastname: Petersen
mesh_terms: D000818:Animals; D019771:Axotomy; D002211:Capsaicin / Q000494:pharmacology*; D002478:Cells, Cultured; D016895:Culture Media, Serum-Free / Q000494:pharmacology; D019004:Galanin / Q000378:metabolism*; D005727:Ganglia, Spinal / Q000166:cytology*; D051100:Glial Cell Line-Derived Neurotrophic Factor; D008297:Male; D020932:Nerve Growth Factor / Q000494:pharmacology; D009414:Nerve Growth Factors / Q000494:pharmacology; D009474:Neurons / Q000166:cytology / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D015854:Up-Regulation
chemical_list: D016895:Culture Media, Serum-Free; C495041:Gdnf protein, rat; D051100:Glial Cell Line-Derived Neurotrophic Factor; D009414:Nerve Growth Factors; D019004:Galanin; D020932:Nerve Growth Factor; D002211:Capsaicin