Evaluation of mechanisms involved in the antinociception of the ethanol extract from the inner bark of Caesalpinia pyramidalis in mice

Ethnopharmacological relevance: Caesalpinia pyramidalis Tul. (Fabaceae) is an endemic tree of the Northeast region of Brazil, mainly in the Caatinga region. More commonly, inner bark or flowers are traditionally used to treat many painful and inflammatory processes. A common use of this plant is made by macerating a handful of its stem bark in a liter of wine or sugarcane brandy. It is drunk against stomachache, dysenteries, and diarrheas. Materials and methods: The ethanol extract of Caesalpinia pyramidalis inner bark was used in mice via oral route, at the doses of 10, 30, and 100 mg/kg, in behavioral models of nociception and investigates some of the mechanisms underlying this effect. Results: The ethanol extract (30 and 100 mg/kg, P <0.001), given orally, produced dose dependent inhibition of acetic acid-induced visceral pain. The ethanol extract also caused significant and dose-dependent inhibition of capsaicin-(100 mg/kg, P <0.001) and glutamate-(10, 30, and 100 mg/kg, P <0.01) induced pain. The antinociception caused by the ethanol extract (30 mg/kg) in the abdominal constriction test was significantly attenuated (P <0.001) by intraperitoneal treatment of mice with L,arginine (600 mg/kg). Conclusions: Collectively, the present results suggest that the ethanol extract of Caesalpinia pyramidalis produced dose-related antinociception in several models of pain through mechanisms that involved both glutamatergic system and/or the L-arginine-nitric oxide pathway, supporting the folkloric usage of the plant to treat various painful processes. (C) 2013 Elsevier Ireland Ltd. All rights reserved.