Antinociceptive effects of galanin in the rat tuberomammillary nucleus and the plasticity of galanin receptor 1 during hyperalgesia.

Abstract

Although the tuberomammillary nucleus (TM) is well defined in terms of anatomy and neurochemistry, little is known about its function in nociceptive modulation. There was an abundance of galanin-immunoreactive fibers in the TM, and galanin has been implicated in pain processing. The present study assessed the role of galanin in the modulation of nociception in the TM of rats. Intra-TM injection of galanin dose-dependently increased the hindpaw withdrawal latency of rats to a noxious thermal stimulus, indicating an antinociceptive role of galanin in the TM. The antinociceptive effect of galanin was blocked by a subsequent intra-TM injection of galantide, a putative galanin receptor antagonist, suggesting that the antinociceptive effect of galanin is mediated by galanin receptors. Moreover, there was abundant galanin receptor 1 (GalR1) in the TM, and the number of GalR1-positive neurons in the ipsilateral TM increased significantly after unilateral loose ligation of the sciatic nerve compared with the contralateral TM or the TM of intact rats. However, the number of GalR1-positive neurons was not significantly altered by carrageenan-induced inflammation, in either the ipsilateral or the contralateral TM. The results suggest that galanin and GalR1 in the TM may play important roles in pain regulation.

• Authors: Yan-Gang Sun, Ji Li, Bo-Ning Yang, Long-Chuan Yu
• Journal: Journal of neuroscience research (J Neurosci Res) Vol. 77 Issue 5 Pg. 718-22 (Sep 01 2004) ISSN: 0360-4012 [Print] United States
• PMID: 15352218 (Publication Type: Comparative Study, Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Receptors, Galanin
• galantide
• Substance P
• Galanin
• Carrageenan

Topics

• Analysis of Variance
• Animals
• Carrageenan
• Dose-Response Relationship, Drug
• Functional Laterality
• Galanin (analogs & derivatives, metabolism, pharmacology, therapeutic use)
• Hyperalgesia (physiopathology)
• Hypothalamic Area, Lateral (drug effects)
• Immunohistochemistry (methods)
• Male
• Neuronal Plasticity (physiology)
• Pain (chemically induced, drug therapy)
• Pain Measurement (methods)
• Physical Stimulation (methods)
• Rats
• Rats, Wistar
• Reaction Time (drug effects)
• Receptors, Galanin (physiology)
• Sciatic Neuropathy (physiopathology)
• Substance P (analogs & derivatives, pharmacology)
• Time Factors