Peripheral mGluR5 antagonist attenuated craniofacial muscle pain and inflammation but not mGluR1 antagonist in lightly anesthetized rats.
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.
Lee
Ho Jeong
HJ
Department of Oral Physiology, School of Dentistry, Kyungpook National University, Daegu, Republic of Korea.
Choi
Hyo Soon
HS
Ju
Jin Sook
JS
Bae
Yong Chul
YC
Kim
Sung Kyo
SK
Yoon
Young Wook
YW
Ahn
Dong Kuk
DK
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
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