Effects of ethanol on deep pain evoked by formalin injected in TMJ of rat.
It has been reported that ethanol can alter nociceptive sensitivity from superficial tissues, such as skin and subcutaneous region. However, the influence of ethanol on deep pain conditions is not understood. The aim of this study was to demonstrate the acute, chronic and ethanol withdrawal effects on nociceptive behavioral responses induced by the injection of formalin into the temporomandibular joint (TMJ) region of rats. In experiment 1, rats were injected with ethanol (2,5 g/Kg, i.p.) or an equal volume of saline 15 min before the administration of formalin (1.5%) into the TMJ. Rats pretreated with ethanol showed a decrease in nociceptive behavioral responses. In experiment 2, rats were given an ethanol solution (6.5%) or tap water to drink for 4 and 10 days. On day 4, the animals (ethanol group) showed amounts of analgesia when submitted to the TMJ formalin test. Tolerance to the antinociceptive effects was observed on day 10. Behavioral hyperalgesia was verified 12 hr after withdrawal in another group that drank ethanol for 10 days. These results show that ethanol can affect the nociceptive responses related to deep pain evoked by the TMJ formalin test.
Laboratory of Orofacial Pain, Faculty of Dentistry of Piracicaba, Department of Physiology, University of Campinas-Unicamp, Av Limeira 901 CP 52, CEP 13414-900, Piracicaba, São Paulo, Brazil. gustavogameiro@yahoo.com.br
Gustavo Hauber
GH
Gameiro
Mariana Trevisani
MT
Arthuri
Cláudia Herrera
CH
Tambeli
Maria Cecília Ferraz
MC
de Arruda Veiga
D000700:Analgesics / Q000008:administration & dosage / Q000494:pharmacology*; D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects; D002492:Central Nervous System Depressants / Q000008:administration & dosage / Q000494:pharmacology*; D004195:Disease Models, Animal; D004347:Drug Interactions; D000431:Ethanol / Q000008:administration & dosage / Q000494:pharmacology*; D007274:Injections, Intraperitoneal; D008297:Male; D010146:Pain / Q000503:physiopathology / Q000517:prevention & control*; D010147:Pain Measurement / Q000187:drug effects*; D017288:Pain Threshold / Q000187:drug effects; D051381:Rats; D017208:Rats, Wistar; D013375:Substance Withdrawal Syndrome / Q000523:psychology; D013704:Temporomandibular Joint / Q000187:drug effects* / Q000503:physiopathology; D014881:Water Supply
D000700:Analgesics; D002492:Central Nervous System Depressants; D000431:Ethanol