Korean J Pain.  2006 Dec;19(2):131-136. 10.3344/kjp.2006.19.2.131.

Potentiation of Morphine's Antinociception by Group II and Group III Metabotropic Glutamate Receptors Agonists on a Rat Incisional Pain

• Kim CM
• Choi JI
• Bae HB
• Kim SJ
• Chung ST
• Kim OH
• Yoon MH

• KMID: 2073917
• DOI: http://doi.org/10.3344/kjp.2006.19.2.131

Abstract

BACKGROUND
The aim of this study was to clarify the role of spinal groups II and III metabotropic glutamate receptors (mGluRs) with respect to postoperative pain at the spinal level. In addition, the nature of the pharmacological interaction between groups II and III mGluRs agonists and morphine was determined. METHODS: Catheters were inserted into the intrathecal space of male SD rats. To induce postoperative pain, an incision was made in the plantar surface of the hind paw. A pharmacological characteristic for the interaction between groups II and III mGluRs agonists and morphine was evaluated using a fixed-dose analysis. RESULTS: None of intrathecal group II and III mGluRs agonists modified the withdrawal threshold of the incisional pain. The administration of intrathecal morphine resulted in an increase of a dose dependent withdrawal threshold. A fixed-dose analysis revealed that the group III mGluRs agonist, ACPT-III, increased the antinociceptive action of morphine, while the group II mGluRs agonist, APDC, had no effect the antinociception of morphine. CONCLUSIONS: These results suggest that group II and III mGluRs may not play a direct modulatory role in the processing of postoperative pain at the spinal level. However, agonizing group III mGluRs may indirectly contributable to the potentiation of morphines antinociception in the spinal cord. Thus, the combination of morphine and a group III mGluRs agonist may be useful in the management of spinal postoperative pain.

Keyword

drug interaction; mGluRs; morphine; postoperative pain; spinal cord; Sprague-Dawley rat

MeSH Terms

Animals
Catheters
Drug Interactions
Felodipine
Humans
Male
Morphine
Morphine Derivatives
Pain, Postoperative
Rats*
Receptors, Metabotropic Glutamate*
Spinal Cord
Felodipine
Morphine
Morphine Derivatives
Receptors, Metabotropic Glutamate