Involvement of peripheral TRPV1 in TMJ hyperalgesia induced by ethanol withdrawal.
Ethanol withdrawal increases nociception after the injection of formalin into the rat's temporomandibular joint (TMJ). Little is known about the neurological basis for hyperalgesia induced by ethanol withdrawal, but it has been reported that ethanol can potentiate the response of transient receptor potential vanilloid receptor-1 (TRPV1) in superficial tissues. The present study was designed to test the hypothesis that peripheral TRPV1 could be involved on nociceptive behavioral responses induced by the injection of formalin into the TMJ region of rats exposed to chronic ethanol administration and ethanol withdrawal. Behavioral hyperalgesia was verified 12 h after ethanol withdrawal in rats that drank an ethanol solution (6.5%) for 10 days. In another group submitted to the same ethanol regimen, the selective vanilloid receptor antagonist capsazepine (300, 600 or 1200 microg/25 microl) or an equal volume of vehicle were injected into the TMJ regions 30 min before the TMJ formalin test. The local injections of capsazepine reduced the increased nociceptive responses induced by ethanol withdrawal. The effect of capsazepine on rats that did not drink ethanol was not significant. These results indicate that the peripheral TRPV1 can contribute to the hyperalgesia induced by ethanol withdrawal on deep pain conditions.
Urtado
Marília Bertoldo
MB
Laboratory of Orofacial Pain, Division of Oral Physiology, Piracicaba Dental School, University of Campinas-Unicamp, Av. Limeira 901 C.P. 52, CEP 13414-900, Piracicaba, São Paulo, Brazil.
Gameiro
Gustavo Hauber
GH
Tambeli
Cláudia Herrera
CH
Fischer
Luana
L
Urtado
Christiano Bertoldo
CB
de Arruda Veiga
Maria Cecília Ferraz
MC
D000818:Animals; D002211:Capsaicin / Q000031:analogs & derivatives / Q000494:pharmacology; D002492:Central Nervous System Depressants / Q000009:adverse effects*; D000431:Ethanol / Q000009:adverse effects*; D005557:Formaldehyde; D008297:Male; D010147:Pain Measurement / Q000187:drug effects; D051381:Rats; D017208:Rats, Wistar; D013375:Substance Withdrawal Syndrome / Q000503:physiopathology*; D050916:TRPV Cation Channels / Q000037:antagonists & inhibitors / Q000187:drug effects / Q000502:physiology*; D013706:Temporomandibular Joint Dysfunction Syndrome / Q000503:physiopathology*
D002492:Central Nervous System Depressants; D050916:TRPV Cation Channels; C493922:Trpv1 protein, rat; D005557:Formaldehyde; D000431:Ethanol; C071423:capsazepine; D002211:Capsaicin