title: WITHDRAWN: Peripheral mGluR5 antagonist attenuated craniofacial muscle pain and inflammation but not mGluR1 antagonist in lightly anesthetized rats.
abstract: The present study investigated the role of peripheral group I metabotropic glutamate receptors (mGluRs) in MO-induced nociceptive behaviour and inflammation in the masseter muscles of lightly anesthetized rats. Experiments were carried out on male Sprague-Dawley rats weighing 300-400 g. After initial anesthesia with sodium pentobarbital (40 mg/kg, i.p.), one femoral vein was cannulated and connected to an infusion pump for intravenous infusion of sodium pentobarbital. The rate of infusion was adjusted to provide a constant level of anesthesia. Mustard oil (MO, 30 microl) was injected into the mid-region of the left masseter muscle via a 30-gauge needle over 10s. After 30 microl injection of 5, 10, 15, or 20% MO into the masseter muscle, the total number of hindpaw shaking behaviour and extravasated Evans' blue dye concentration in the masseter muscle were significantly higher in the MO-treated group in a dose-dependent manner compared with the vehicle (mineral oil)-treated group. Intramuscular pretreatment with 3 or 5% lidocaine reduced MO-induced hindpaw shaking behaviour and increases in extravasated Evans' blue dye concentration. Intramuscular pretreatment with 5mM MCPG, non-selective group I/II mGluR antagonist, or MPEP, a selective group I mGluR5 antagonist, produced a significant attenuation of MO-induced hindpaw shaking behaviour and increases in extravasated Evans' blue dye concentration in the masseter muscle while LY367385, a selective group I mGluR1 antagonist, did not affect MO-induced nociceptive behaviour and inflammation in the masseter muscle. These results indicate that peripheral mGluR5 plays important role in mediating MO-induced nociceptive behaviour and inflammation in the craniofacial muscle.
authors.affiliation: Department of Oral Physiology, School of Dentistry, Kyungpook National University, 188-1 Sam Deok 2ga, Chung-gu, Daegu (700-412), Republic of Korea.
authors.forename: Ho Jeong
authors.initials: HJ
authors.lastname: Lee
authors.forename: Hyo Soon
authors.initials: HS
authors.lastname: Choi
authors.forename: Jin Sook
authors.initials: JS
authors.lastname: Ju
authors.forename: Yong Chul
authors.initials: YC
authors.lastname: Bae
authors.forename: Sung Kyo
authors.initials: SK
authors.lastname: Kim
authors.forename: Young Wook
authors.initials: YW
authors.lastname: Yoon
authors.forename: Dong Kuk
authors.initials: DK
authors.lastname: Ahn