KMID : 0811720080120050237
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Korean Journal of Physiology & Pharmacology 2008 Volume.12 No. 5 p.237 ~ p.244
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Spinal Metabotropic Glutamate Receptors (mGluRs) are Involved in the Melittin-induced Nociception in Rats
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Cho Chul-Hyun
Shin Hong-Kee
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Abstract
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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 (10?g/paw) into the mid-plantar area of rat hindpaw. To observe the effects of mGluRs on the melittin-induced nociceptions, group I mGluR (AIDA, 100?g and 200?g), mGluR1 (LY367385, 50?g and 100?g) and mGluR5 (MPEP, 200?g and 300?g) antagonists, group II (APDC, 100?g and 200?g) and III (L-SOP, 100?g and 200?g) 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.
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KEYWORD
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Spinal metabotropic glutamate receptors, Melittin, Nociceptive responses
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