Galanin expression in neuropathic pain: friend or foe?

Abstract

We investigated a possible link between galanin expression and evoked pain accompanying painful partial sciatic nerve lesions. Increased galanin immunoreactivity (IR) in the dorsal horn, in gracile nucleus, and in sensory neurons following chronic constriction injury (CCI) compared to complete sciatic transection suggested a facilitatory role in thermal and mechanical hypersensitivity (allodynia). We therefore investigated the effects of endogenous interleukin-6 (IL-6) and nerve growth factor (NGF) on allodynia and neuropeptide expression. IL-6 knockout mice showed decreased allodynia and galanin-IR compared to wild-type mice, but also decreased substance P (SP)-IR in the dorsal horn. Anti-NGF-treated rats with CCI also showed decreased allodynia and SP-IR, but increased galanin-IR in the dorsal horn. These results suggest that evoked pain is more tightly linked to SP than to galanin expression. If galanin's effects are inhibitory as the bulk of the literature suggests, its effects are subordinate to those of SP and to other changes following CCI.

• Authors: M S Ramer, W Ma, P G Murphy, P M Richardson, M A Bisby
• Journal: Annals of the New York Academy of Sciences (Ann N Y Acad Sci) Vol. 863 Pg. 390-401 (Dec 21 1998) ISSN: 0077-8923 [Print] United States
• PMID: 9928185 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't, Review)

Chemical References

• Interleukin-6
• Nerve Growth Factors
• Galanin

Topics

• Animals
• Galanin (physiology)
• Interleukin-6 (physiology)
• Mice
• Nerve Growth Factors (physiology)
• Pain (physiopathology)
• Peripheral Nervous System (injuries, physiopathology)
• Rats