title: Attenuation of capsaicin-induced acute and visceral nociceptive pain by alpha- and beta-amyrin, a triterpene mixture isolated from Protium heptaphyllum resin in mice.
abstract: The triterpene mixture, alpha- and beta-amyrin, isolated from Protium heptaphyllum resin was evaluated on capsaicin-evoked nociception in mice. Orally administered alpha- and beta-amyrin (3 to 100 mg/kg) significantly suppressed the nociceptive behaviors--evoked by either subplantar (1.6 microg) or intracolonic (149 microg) application of capsaicin. The antinociception produced by alpha- and beta-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 alpha2-adrenoceptor involvement was unlikely since yohimbine (2 mg/kg, i.p.) pretreatment failed to block the antinociceptive effect of alpha- and beta-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, alpha- and beta-amyrin could significantly block the capsaicin (10 mg/kg, s.c.)-induced hyperthermic response but not the initial hypothermia. These results suggest that the triterpene mixture, alpha- and beta-amyrin has an analgesia inducing effect, possibly involving vanilloid receptor (TRPV1) and an opioid mechanism.
authors.affiliation: Departamento de Fisiologia e Farmacologia, Universidade Federal do Ceará, Rua Cel Nunes de Melo-1127, Caixa Postal-3157, 60430-270, Fortaleza, CE, Brazil.
authors.forename: Francisco A
authors.initials: FA
authors.lastname: Oliveira
authors.forename: Charllynton L S
authors.initials: CL
authors.lastname: Costa
authors.forename: Mariana H
authors.initials: MH
authors.lastname: Chaves
authors.forename: Fernanda R C
authors.initials: FR
authors.lastname: Almeida
authors.forename: Italo J M
authors.initials: IJ
authors.lastname: Cavalcante
authors.forename: Alana F
authors.initials: AF
authors.lastname: Lima
authors.forename: Roberto C P
authors.initials: RC
authors.lastname: Lima
authors.forename: Regilane M
authors.initials: RM
authors.lastname: Silva
authors.forename: Adriana Rolim
authors.initials: AR
authors.lastname: Campos
authors.forename: Flavia A
authors.initials: FA
authors.lastname: Santos
authors.forename: Vietla S N
authors.initials: VS
authors.lastname: Rao
mesh_terms: D000284:Administration, Oral; D000700:Analgesics / Q000494:pharmacology / Q000627:therapeutic use*; D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects; D029403:Burseraceae / Q000737:chemistry*; D002211:Capsaicin / Q000008:administration & dosage; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D004338:Drug Combinations; D007035:Hypothermia / Q000139:chemically induced; D051379:Mice; D009043:Motor Activity / Q000187:drug effects; D009828:Oleanolic Acid / Q000031:analogs & derivatives* / Q000494:pharmacology / Q000627:therapeutic use; D010146:Pain / Q000139:chemically induced / Q000188:drug therapy*; D004856:Postural Balance / Q000187:drug effects; D012116:Resins, Plant / Q000494:pharmacology / Q000627:therapeutic use; D012890:Sleep / Q000187:drug effects
chemical_list: D000700:Analgesics; D004338:Drug Combinations; D012116:Resins, Plant; D009828:Oleanolic Acid; C036380:beta-amyrin; D002211:Capsaicin