title: CB1 and CB2 contribute to antinociceptive and anti-inflammatory effects of electroacupuncture on experimental arthritis of the rat temporomandibular joint.
abstract: Electroacupuncture (EA) and cannabinoids have been reported to have anti-inflammatory and antinociceptive effects in animal models of arthritis. Male Wistar rats were injected with saline or zymosan (2 mg) into the temporomandibular joint (TMJ). EA (10 Hz, 30 min) was performed 2 h after or 1 h before zymosan administration. AM251 or AM630 (3 mg/kg, i.p.)were administered before EA treatment. Mechanical hypernociception was accessed after zymosan administration. Rats were sacrificed 6 h after zymosan administration and the joint was removed for histopathological analysis. The gene expression of CB₁ and CB₂ receptors was assessed after sacrifice of the TMJ arthritic animals. EA inhibited zymosan-induced hypernociception (p < 0.05). AM251 reversed significantly the antinociceptive effect of EA, suggesting that the CB₁ receptor is involved in this effect. AM630 reversed the anti-inflammatory effect of EA. CB₁ and CB₂ receptor gene expression was upregulated 6 h after zymosan-induced arthritis in the EA-treated group. We observed downregulation of CB₂ receptor gene expression in the EA group at the 24th hour compared with the 6th hour. Higher CB₁ receptor gene expression was also found compared with the 6th hour. EA produced antinociceptive and anti-inflammatory effects, and these effects appeared to be mediated through CB₁ and CB₂ receptor activation.
authors.affiliation: Medical Sciences Post-Graduation, Faculty of Medicine, Federal University of Ceará, Fortaleza, Brazil. delanegondim@yahoo.com.br
authors.forename: Delane Viana
authors.initials: DV
authors.lastname: Gondim
authors.forename: Joana Cláudia Bezerra
authors.initials: JC
authors.lastname: Araújo
authors.forename: André Luiz Cunha
authors.initials: AL
authors.lastname: Cavalcante
authors.forename: Alexandre
authors.initials: A
authors.lastname: Havt
authors.forename: Josiane da Siva
authors.initials: Jda S
authors.lastname: Quetz
authors.forename: Gerly Anne de Castro
authors.initials: GA
authors.lastname: Brito
authors.forename: Ronaldo de Albuquerque
authors.initials: Rde A
authors.lastname: Ribeiro
authors.forename: Mariana
authors.initials: M
authors.lastname: Lima Vale
mesh_terms: D015667:Acupuncture Analgesia / Q000379:methods; D000818:Animals; D001169:Arthritis, Experimental / Q000276:immunology / Q000378:metabolism / Q000517:prevention & control / Q000628:therapy*; D001522:Behavior, Animal / Q000187:drug effects; D015536:Down-Regulation; D015671:Electroacupuncture; D007211:Indoles / Q000494:pharmacology; D008297:Male; D009419:Nerve Tissue Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D059225:Nociception / Q000187:drug effects; D010880:Piperidines / Q000494:pharmacology; D011720:Pyrazoles / Q000494:pharmacology; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D043884:Receptor, Cannabinoid, CB1 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D043885:Receptor, Cannabinoid, CB2 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D013704:Temporomandibular Joint / Q000187:drug effects / Q000276:immunology* / Q000294:innervation / Q000473:pathology; D014279:Trigeminal Nucleus, Spinal / Q000187:drug effects / Q000276:immunology / Q000378:metabolism* / Q000473:pathology; D015854:Up-Regulation; D015054:Zymosan
chemical_list: C543264:Cnr1 protein, rat; C469526:Cnr2 protein, rat; D007211:Indoles; D009419:Nerve Tissue Proteins; D010880:Piperidines; D011720:Pyrazoles; D012333:RNA, Messenger; D043884:Receptor, Cannabinoid, CB1; D043885:Receptor, Cannabinoid, CB2; C103505:AM 251; D015054:Zymosan; C094023:iodopravadoline