Peripheral sympathetic component of the temporomandibular joint inflammatory pain in rats.
The aim of this study was to further validate our carrageenan-induced temporomandibular joint (TMJ) inflammatory hyperalgesia model in rats by showing that administration of indomethacin before the initiation of inflammation would diminish the TMJ hyperalgesia. Using this model, we investigated whether norepinephrine and local beta-adrenoceptors contribute to the development of inflammatory TMJ hyperalgesia. Carrageenan-induced TMJ hyperalgesia was assessed by measuring the behavioral nociceptive responses, such as rubbing the orofacial region and flinching the head, induced by the injection of a low dose of 5-hydroxytryptamine into the TMJ sensitized 1 h before by a TMJ injection of carrageenan. Blockade of prostaglandin synthesis by indomethacin prior to initiation of inflammation by carrageenan significantly attenuated the TMJ hyperalgesia. The guanethidine depletion of norepinephrine or the blockade of beta(2)but not the blockade of the beta(1)-adrenoceptor by the selective adrenoceptor antagonists ICI 118.55 and atenolol, respectively, significantly reduced carrageenan-induced TMJ hyperalgesia. In the present study, we further validated our carrageenan-induced TMJ hyperalgesia model to study the mechanisms involved in inflammatory TMJ hyperalgesia and to test the analgesic effect of different types of peripheral analgesics. We also demonstrated that norepinephrine released at the site of injury contributes to the development of the inflammatory TMJ hyperalgesia by the activation of beta(2)-adrenoceptors.


CONCLUSIONS
The findings that local sympathomimetic amines contribute to the inflammatory TMJ hyperalgesia by activating beta(2)-adrenoceptors may be relevant to clinical TMJ inflammatory pain states less sensitive to nonsteroidal anti-inflammatory drugs.
Rodrigues
Luciane Lacerda Franco Rocha
LL
Department of Physiology, Laboratory of Orofacial Pain, Faculty of Dentistry of Piracicaba, University of Campinas-UNICAMP, São Paulo, Brazil.
Oliveira
Maria Cláudia Gonçalves
MC
Pelegrini-da-Silva
Adriana
A
de Arruda Veiga
Maria Cecília Ferraz
MC
Parada
Carlos Amílcar
CA
Tambeli
Cláudia Herrera
CH
D000319:Adrenergic beta-Antagonists / Q000627:therapeutic use; D000818:Animals; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000627:therapeutic use; D002351:Carrageenan; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D005157:Facial Pain / Q000139:chemically induced / Q000188:drug therapy / Q000503:physiopathology*; D007839:Functional Laterality; D007213:Indomethacin / Q000627:therapeutic use; D008297:Male; D010147:Pain Measurement / Q000379:methods; D017288:Pain Threshold / Q000187:drug effects / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar; D011930:Reaction Time / Q000187:drug effects; D012701:Serotonin / Q000627:therapeutic use; D013564:Sympathetic Nervous System / Q000187:drug effects / Q000503:physiopathology*; D013705:Temporomandibular Joint Disorders / Q000139:chemically induced / Q000188:drug therapy / Q000503:physiopathology*
D000319:Adrenergic beta-Antagonists; D000894:Anti-Inflammatory Agents, Non-Steroidal; D012701:Serotonin; D002351:Carrageenan; D007213:Indomethacin