Systemic galnon, a low-molecular weight galanin receptor agonist, reduces heat hyperalgesia in rats with nerve injury.
We have examined the effect of systemically administered galnon, a novel low-molecular weight agonist of galanin receptors, on neuropathic pain-like behaviors in rats after photochemically induced partial nerve injury. Galnon is a galanin receptor ligand with moderate affinity to spinal cord membranes (K(D) of 6+/-0.6 microM). While intraperitoneally applied galnon produced no significant effect on mechanical or cold hypersensitivity, it dose-dependently prolonged heat withdrawal latency in nerve-injured rats. The effect of galnon was more potent on the injured side which has significantly shorter latency than the contralateral side. The anti-hyperalgesic effect of galanon was prevented by intrathecal M35, a galanin receptor antagonist. No side effects, such as sedation or motor impairment, were seen following systemic galnon treatment at the doses used. It is concluded that systemic galnon alleviated heat-hyperalgesic response in rats with partial sciatic nerve injury. This effect was likely to be mediated by activation of spinal galanin receptors.
Wu
Wei-Ping
WP
Department of Medical Laboratory Sciences and Technology, Division of Clinical Neurophysiology, Huddinge University Hospital, Karolinska Institutet, S-141 86 Stockholm, Sweden.
Hao
Jing-Xia
JX
Lundström
Linda
L
Wiesenfeld-Hallin
Zsuzsanna
Z
Langel
Ulo
U
Bartfai
Tamas
T
Xu
Xiao-Jun
XJ
D000818:Animals; D003374:Coumarins / Q000008:administration & dosage*; D006358:Hot Temperature / Q000009:adverse effects*; D006930:Hyperalgesia / Q000188:drug therapy*; D008297:Male; D010147:Pain Measurement / Q000187:drug effects; D051381:Rats; D017207:Rats, Sprague-Dawley; D044088:Receptors, Galanin / Q000819:agonists* / Q000502:physiology; D020426:Sciatic Neuropathy / Q000188:drug therapy*
C456547:7-((9-fluorenylmethoxycarbonyl)cyclohexylalanyllysyl)amino-4-methylcoumarin; D003374:Coumarins; D044088:Receptors, Galanin