Abstract
In the search for novel natural compounds effective against visceral nociception, the triterpenoid mixture α- and β-amyrin, isolated from Protium heptaphyllum resin, was assessed in two established mouse models of visceral nociception. Mice were pretreated orally with α- and β-amyrin (3, 10, 30, and 100 mg/kg) or vehicle, and the pain-related behavioral responses to intraperitoneal cyclophosphamide or to intracolonic mustard oil were analyzed. The triterpenoid mixture showed a dose-related significant antinociception against the cyclophosphamide-induced bladder pain, and at 100 mg/kg, the nociceptive behavioral expression was almost completely suppressed. Intracolonic mustard oil-induced nociceptive behaviors were maximally inhibited by 10 mg/kg α- and β-amyrin mixture in a naloxone-reversible manner. While pretreatment with ruthenium red (3 mg/kg, s. c. ), a non-specific transient receptor potential cation channel V1 (TRPV1) antagonist, also caused significant inhibition, the α2 -adrenoceptor antagonist, yohimbine (2 mg/kg, s. c. ), showed no significant effect. The triterpene mixture (10 mg/kg, p. o. ) neither altered significantly the pentobarbital sleeping time, nor impaired the ambulation or motor coordination in open-field and rotarod tests, respectively, indicating the absence of sedative or motor abnormalities that could account for its antinociception. These results indicate that the antinociceptive potential of α- and β-amyrin possibly involves the opioid and vanilloid (TRPV1) receptor mechanisms and further suggests that it could be useful to treat visceral pain of intestinal and pelvic origins.
Key words
Protium heptaphyllum
- Burseraceae - triterpenoid mixture - α- and β-amyrin - visceral nociception - mouse model
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vietrao@ufc.br
