Elsevier

Neuropeptides

Volume 33, Issue 4, August 1999, Pages 281-284
Neuropeptides

Regular Article
Endomorphin-1 reduces carrageenan-induced Fos expression in the rat spinal dorsal horn

https://doi.org/10.1054/npep.1999.0040Get rights and content

Abstract

Intraplantar injection of carrageenan induced significant Fos expression in the superficial and deep spinal dorsal horn at the L4–L5segments and extensive peripheral edema of the ipsilateral foot in rats. Intraplantar injection of endomorphin-1, endogenous ligand for μ opioid receptor, in the same region produced dose-dependent reduction of carrageenan-induced Fos expression and peripheral edema, which were completely blocked by co-administration of intraplantar injection of naloxone (20 μg). The systemic injection of the highest dose of endomorphin-1 (50 μg) had no significant reductory effect on Fos expression and peripheral edema. These results further provided a strong evidence for involvement of μ opioid receptor in peripheral analgesia, particularly in inflammation pain.

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