Spinal Metabotropic Glutamate Receptors (mGluRs) are Involved in the Melittin-induced Nociception in Rats.
10.4196/kjpp.2008.12.5.237
- Author:
Chul Hyun CHO
1
;
Hong Kee SHIN
Author Information
1. Department of Orthopedic Surgery, School of Medicine, Keimyung University, Daegu, Korea.
- Publication Type:Original Article
- Keywords:
Spinal metabotropic glutamate receptors;
Melittin;
Nociceptive responses
- MeSH:
Animals;
Edema;
Melitten;
Nociception;
Rats;
Receptors, Metabotropic Glutamate
- From:The Korean Journal of Physiology and Pharmacology
2008;12(5):237-243
- CountryRepublic of Korea
- Language:English
-
Abstract:
Intraplantar injection of melittin has been known to induce sustained decrease of mechanical threshold and increase of spontaneous flinchings. The present study was undertaken to investigate how the melittin-induced nociceptive responses were modulated by changes of metabotropic glutamate receptor (mGluR) activity. Changes in paw withdrawal threshold (PWT), number of flinchings and paw thickness were measured at a given time point after injection of melittin (10microgram/paw) into the mid-plantar area of rat hindpaw. To observe the effects of mGluRs on the melittin-induced nociceptions, group I mGluR (AIDA, 100microgram and 200microgram), mGluR1 (LY367385, 50microgram and 100microgram) and mGluR5 (MPEP, 200microgram and 300microgram) antagonists, group II (APDC, 100microgram and 200microgram) and III (L-SOP, 100microgram and 200microgram) agonists were intrathecally administered 20 min before melittin injection. Intraplantar injection of melittin induced a sustained decrease of mechanical threshold, spontaneous flinchings and edema. The effects of melittin to reduce mechanical threshold and to induce spontaneous flinchings were significantly suppressed following intrathecal pre-administration of group I mGluR, mGluR1 and mGluR5 antagonists, group II and III mGluR agonists. Group I mGluR antagonists and group II and III mGluR agonists had no significant effect on melittin-induced edema. These experimental findings indicate that multiple spinal mGluRs are involved in the modulation of melittin-induced nociceptive responses.
