Attenuation of capsaicin-induced acute and visceral nociceptive pain by a - and h -amyrin, a triterpene mixture isolated from Protium heptaphyllum resin in mice

• Autor(a) principal: Oliveira, Francisco A.
• Data de Publicação: 2005
• Outros Autores: Costa, Charllynton L.S., Chaves, Mariana H.0, Almeida, Fernanda Regina de Castro, Cavalcante, Ítalo José Mesquita, Lima, Alana Fonteles, Lima Jr., Roberto César Pereira, Silva, Regilane M., Campos, Adriana Rolim, Santos, Flavia Almeida, Rao, Vietla Satyanarayana
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Institucional da Universidade Federal do Ceará (UFC)
• Texto Completo: http://www.repositorio.ufc.br/handle/riufc/5603
• topic: Capsaicina; Ratos

The triterpene mixture, a - and h -amyrin, isolated from Protium heptaphyllum resin was evaluated on capsaicin- evoked nociception in mice. Orally administered a - and h -amyrin (3 to 100 mg/kg) significantly suppressed the nociceptive behaviors—evoked by either subplantar (1.6 A g) or intracolonic (149 A g) application of capsaicin. The antinociception produced by a - and h -amyrin against subplantar capsaicin-induced paw-licking behavior was neither potentiated nor attenuated by ruthenium red (1.5 mg/kg, s.c.), a non-specific antagonist of vanilloid receptor (TRPV1), but was greatly abolished in animals pretreated with naloxone (2 mg/kg, s.c.), suggesting an opioid mechanism. However, participation of a 2 -adrenoceptor involvement was unlikely since yohimbine (2 mg/ kg, i.p.) pretreatment failed to block the antinociceptive effect of a - and h -amyrin in the experimental model of visceral nociception evoked by intracolonic capsaicin. The triterpene mixture (3 to 30 mg/kg, p.o.) neither altered significantly the pentobarbital sleeping time, nor impaired the ambulation or motor coordination in open-field and rota-rod tests, respectively, indicating the absence of sedative or motor abnormality that could account for its antinociception. Nevertheless, a - and h -amyrin could significantly block the capsaicin (10 mg/kg, s.c.)-induced