title: 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 5 mM 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, Daegu, 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
mesh_terms: D000779:Anesthetics, Local / Q000627:therapeutic use*; D000818:Animals; D001522:Behavior, Animal; D001565:Benzoates / Q000627:therapeutic use; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D018691:Excitatory Amino Acid Antagonists / Q000627:therapeutic use*; D005152:Facial Muscles / Q000187:drug effects* / Q000503:physiopathology; D005157:Facial Pain / Q000139:chemically induced / Q000188:drug therapy*; D007839:Functional Laterality / Q000187:drug effects; D005998:Glycine / Q000031:analogs & derivatives / Q000627:therapeutic use; D007249:Inflammation / Q000139:chemically induced / Q000188:drug therapy*; D008012:Lidocaine / Q000627:therapeutic use*; D008297:Male; D009149:Mustard Plant; D010147:Pain Measurement / Q000379:methods; D010938:Plant Oils; D011725:Pyridines / Q000627:therapeutic use; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D000779:Anesthetics, Local; D001565:Benzoates; D018691:Excitatory Amino Acid Antagonists; D010938:Plant Oils; D011725:Pyridines; C474696:methyl-(4-carboxyphenyl)glycine; C079694:alpha-methyl-4-carboxyphenylglycine; C121465:6-methyl-2-(phenylethynyl)pyridine; D008012:Lidocaine; D005998:Glycine; C027793:mustard oil