RESUMO
The effect of intrathecal administration of the GABA(A) receptor antagonist bicuculline methylbromide on jaw muscle electromyographic (EMG) activity evoked by mustard oil injection into the rat temporomandibular joint was studied. Bicuculline given prior to mustard oil augmented the EMG activity evoked by mustard oil, and "rekindling" of EMG activity was induced by bicuculline given 30 min after mustard oil. These results suggest that central GABA(A) receptors modulate reflex responses to noxious craniofacial stimuli.
Assuntos
Bicuculina/análogos & derivados , Bicuculina/farmacologia , Músculos da Mastigação/fisiologia , Extratos Vegetais/farmacologia , Receptores de GABA-A/fisiologia , Articulação Temporomandibular/fisiologia , Animais , Bicuculina/administração & dosagem , Esquema de Medicação , Eletromiografia/efeitos dos fármacos , Lateralidade Funcional , Antagonistas GABAérgicos/administração & dosagem , Antagonistas GABAérgicos/farmacologia , Injeções Espinhais , Masculino , Músculo Masseter/efeitos dos fármacos , Músculo Masseter/inervação , Músculo Masseter/fisiologia , Músculos da Mastigação/efeitos dos fármacos , Músculos da Mastigação/inervação , Microinjeções , Mostardeira , Extratos Vegetais/administração & dosagem , Óleos de Plantas , Plantas Medicinais , Ratos , Ratos Sprague-Dawley , Receptores de GABA-A/efeitos dos fármacos , Articulação Temporomandibular/efeitos dos fármacosRESUMO
Postnatal changes in the electromyographic (EMG) activity of jaw muscles evoked by mustard oil (MO) application into the rat temporomandibular joint region and the recurrence of increased jaw muscle activities after intravenous injection of naloxone were compared among 4, 6 and 8-week-old rats. In all the groups, MO application increased EMG activity on the ipsilateral side, however, 4-week old rats showed only a small increase in EMG activity on the contralateral side. The EMG activity on the contralateral side increased in an age-dependent manner. The recurrence of increased jaw muscle activity was not induced in 4-week old rats. These results suggest that a neural circuit for generating contralateral responses and mechanisms for central excitation are not established until after 4 weeks postnatally.