title: Reduced spinal cord sensitization to C-fibre stimulation in mice over-expressing galanin.
abstract: The neuropeptide galanin may have a role in spinal nociception. In this study, we examined the excitability of the flexor reflex and its sensitization by repetitive stimulation of nociceptive C-fibres in anaesthetized mice that over-express galanin. No difference was seen between over-expressing galanin and wild-type mice in the magnitude of the baseline flexor reflex. Repetitive conditioning stimulation of C-fibres (10 stimuli at 1 Hz) produced a gradual increase in reflex magnitude during the conditioning stimulation (wind-up), as well as an increase in spinal reflex excitability after the termination of the stimulus train (central sensitization) in wild-type mice. Although the wind-up did not differ between over-expressing galanin and wild-type mice, the magnitude of central sensitization was significantly reduced in the over-expressing galanin mice (24 +/- 13% peak increase compared with 164 +/- 65% in the wild-type). Intrathecal administration of M35, a galanin receptor antagonist, markedly enhanced central sensitization in over-expressing galanin mice in association with C-fibre conditioning stimulation, while having no effect in wild-type mice. These results provide further electrophysiological evidence for an inhibitory function of galanin in modulation of central sensitization in response to C-fibre stimulation.
authors.affiliation: Department of Laboratory Medicine, Division of Clinical Neurophysiology, Huddinge University Hospital, Karolinska Institutet, Stockholm, Sweden SE-14186. stefan.grass@labmed.ki.se
authors.forename: Stefan
authors.initials: S
authors.lastname: Grass
authors.forename: Jacqueline N
authors.initials: JN
authors.lastname: Crawley
authors.forename: Xiao-Jun
authors.initials: XJ
authors.lastname: Xu
authors.forename: Zsuzsanna
authors.initials: Z
authors.lastname: Wiesenfeld-Hallin
mesh_terms: D000818:Animals; D003213:Conditioning, Psychological / Q000187:drug effects / Q000502:physiology; D004558:Electric Stimulation / Q000379:methods; D005260:Female; D019004:Galanin / Q000096:biosynthesis* / Q000235:genetics*; D005786:Gene Expression Regulation / Q000502:physiology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D036421:Nerve Fibers, Unmyelinated / Q000187:drug effects / Q000378:metabolism*; D018408:Patch-Clamp Techniques; D013116:Spinal Cord / Q000187:drug effects / Q000378:metabolism*
chemical_list: D019004:Galanin