title: Role of peripheral group I and II metabotropic glutamate receptors in IL-1beta-induced mechanical allodynia in the orofacial area of conscious rats.
abstract: The present study investigated the role of peripheral group I and II metabotropic glutamate receptors (mGluRs) in interleukin-1beta (IL-1beta)-induced mechanical allodynia in the orofacial area. Experiments were carried out on Sprague-Dawley rats weighing between 230 and 280 g. After subcutaneous administration of 0.01, 0.1, 1, or 10 pg of IL-1beta, we examined withdrawal behavioral responses produced by 10 successive trials of a ramp of air-puffs pressure applied ipsilaterally or contralaterally to the IL-1beta injection site. The thresholds of air puffs were measured 10, 30, 60, 120, or 180 min after 25 microl of IL-1beta was administered through an implanted tube. Subcutaneous injection of IL-1beta produced bilateral mechanical allodynia. While the IL-1beta-induced mechanical allodynia was blocked by pretreatment with an IL-1 receptor antagonist, the IL-1beta-induced mirror-image mechanical allodynia was not blocked by an IL-1 receptor antagonist injected into the contralateral side. Subcutaneous administration of CPCCOEt or LY367385, an mGluR1 antagonist, or MPEP or SIB1893, an mGluR5 antagonist, 10 min prior to injection of IL-1beta abolished IL-1beta-induced mechanical allodynia. Pretreatment with APDC or DCG4, a group II mGluR agonist, blocked the IL-1beta-induced mechanical allodynia. The anti-allodynic effect induced by APDC was inhibited by pretreatment with LY341495, a group II mGluR antagonist. These results suggest that peripheral group I and II mGluRs participate in IL-1beta-induced mechanical allodynia in the orofacial area. Peripheral group I mGluR antagonists blocked the IL-1beta-induced mechanical allodynia, while peripheral group II mGluR agonists produced anti-allodynic effects on IL-1beta-induced mechanical allodynia in the orofacial area of rats.
authors.affiliation: Department of Oral Physiology and Neurobiology, School of Dentistry, Kyungpook National University, 188-1 Sam Deok 2 ga, Chung-gu, Daegu 700 412, South Korea. dkahn@mail.knu.ac.kr
authors.forename: Dong K
authors.initials: DK
authors.lastname: Ahn
authors.forename: Kwang H
authors.initials: KH
authors.lastname: Kim
authors.forename: Chang Y
authors.initials: CY
authors.lastname: Jung
authors.forename: Hyo S
authors.initials: HS
authors.lastname: Choi
authors.forename: Eun J
authors.initials: EJ
authors.lastname: Lim
authors.forename: Dong H
authors.initials: DH
authors.lastname: Youn
authors.forename: Yong C
authors.initials: YC
authors.lastname: Bae
mesh_terms: D000388:Air; D000818:Animals; D001565:Benzoates / Q000494:pharmacology; D002867:Chromones / Q000494:pharmacology; D003243:Consciousness / Q000502:physiology; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D005157:Facial Pain / Q000139:chemically induced* / Q000503:physiopathology* / Q000517:prevention & control; D007839:Functional Laterality; D005998:Glycine / Q000031:analogs & derivatives / Q000494:pharmacology; D007279:Injections, Subcutaneous; D007375:Interleukin-1; D008297:Male; D009619:Nociceptors / Q000502:physiology*; D010147:Pain Measurement; D017288:Pain Threshold / Q000502:physiology; D010812:Physical Stimulation / Q000379:methods*; D011725:Pyridines / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D018094:Receptors, Metabotropic Glutamate / Q000037:antagonists & inhibitors / Q000502:physiology*
chemical_list: C117789:7-(hydroxyimino)cyclopropan(b)chromen-1a-carbxoylic acid ethyl ester; D001565:Benzoates; D002867:Chromones; D018691:Excitatory Amino Acid Antagonists; D007375:Interleukin-1; D011725:Pyridines; D018094:Receptors, Metabotropic Glutamate; C120148:SIB 1893; C079694:alpha-methyl-4-carboxyphenylglycine; D005998:Glycine