Local peripheral effects of mu-opioid receptor agonists in neuropathic pain in rats.

Abstract

Our study was designed to demonstrate peripheral antinociception of the mu-opioid receptor agonists: morphine (MF), [D-Ala(2), N-Me-Phe(4), Gly(5)-ol]enkephalin (DAMGO), endomorphin-1 (EM-1) and endomorphin-2 (EM-2) in Bennett's rat model of neuropathic pain. All the agonists were effective in antagonizing allodynia after their intraplantar (i.pl.) but not subcutaneous (s.c.) administration. Opioid peptides: DAMGO, EM-1 and EM-2 were more effective compared with corresponding doses of morphine (opioid alkaloid) in alleviating chronic pain. Peripheral mu-opioid receptors mediated the observed effects, as was evidenced by the i.pl. treatment with naloxone methiodide (active only at the site of injection) and by cyprodime, a selective mu-opioid receptor antagonist. These results have shown that opioid peptides are effective also after local treatment, and that their peripheral use may be of therapeutic interest in long-term management of chronic pain.

• Authors: Ilona Obara, Ryszard Przewlocki, Barbara Przewlocka
• Journal: Neuroscience letters (Neurosci Lett) Vol. 360 Issue 1-2 Pg. 85-9 (Apr 22 2004) ISSN: 0304-3940 [Print] Ireland
• PMID: 15082185 (Publication Type: Comparative Study, Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Analgesics, Opioid
• Receptors, Opioid, mu

Topics

• Analgesics, Opioid (administration & dosage)
• Animals
• Dose-Response Relationship, Drug
• Male
• Pain (drug therapy)
• Pain Measurement (drug effects, methods)
• Rats
• Rats, Wistar
• Receptors, Opioid, mu (agonists, physiology)
• Sciatic Neuropathy (drug therapy)