Antinociceptive effect of Lecythis pisonis Camb. (Lecythidaceae) in models of acute pain in mice

AbstractEthnopharmacological relevanceLecythis pisonis Camb., also known in Brazil as sapucaia, is used in folk medicine against pruritus, muscle pain and gastric ulcer.Aim of the studyTo investigate the antinociceptive effect of ethanol extract from Lecythis pisonis leaves (LPEE), fractions (hexane-LPHF, ether-LPEF and ethyl acetate-LPEAF) and mixture of triterpenes [ursolic and oleanolic acids (MT)] in mice.Materials and methodsLPEE and LPEF were evaluated on the acetic acid induced writhings and formalin, capsaicin and glutamate tests. In addition, MT was investigated on the writhings induced by acetic acid, capsaicin and glutamate tests. In the study of some possible mechanisms involved on the antinociceptive effect of LPEF, it was investigated the participation of opioid system, K+ATP channels and l-arginine-nitric oxide pathway.ResultsLPEE (12.5 and 25mg/kg, p.o.), LPEF and MT (6.25, 12.5 and 25mg/kg, p.o.) reduced the writhings in comparison to saline. LPEE (100mg/kg, p.o.) and LPEF (50mg/kg, p.o.) were effective in inhibiting both phases of formalin test. In capsaicin test, LPEE (100 and 200mg/kg, p.o.), LPEF (12.5–50mg/kg, p.o) and MT (6.25–25mg/kg, p.o.) showed a significant antinociceptive effect compared to the control. LPEE (25 and 50mg/kg, p.o.), LPEF (50 and 100mg/kg, p.o.) and MT (12.5 and 25mg/kg, p.o.) reduced the glutamate-evoked nociceptive response. Treatment with naloxone, l-arginine and glibenclamide reversed the effect of LPEF in glutamate test.ConclusionsThese results indicate the antinociceptive effect of Lecythis pisonis leaves and suggest that this effect may be related to opioid pathway, K+ATP channels, and l-arginine-nitric oxide modulation. Furthermore, these data support the ethnomedical use of this plant