title: Antinociceptive effect of Lecythis pisonis Camb. (Lecythidaceae) in models of acute pain in mice.
abstract: BACKGROUND
  Lecythis pisonis Camb., also known in Brazil as sapucaia, is used in folk medicine against pruritus, muscle pain and gastric ulcer.
  
  
  OBJECTIVE
  To 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.
  
  
  METHODS
  LPEE 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.
  
  
  RESULTS
  LPEE (12.5 and 25 mg/kg, p.o.), LPEF and MT (6.25, 12.5 and 25 mg/kg, p.o.) reduced the writhings in comparison to saline. LPEE (100 mg/kg, p.o.) and LPEF (50 mg/kg, p.o.) were effective in inhibiting both phases of formalin test. In capsaicin test, LPEE (100 and 200 mg/kg, p.o.), LPEF (12.5-50 mg/kg, p.o) and MT (6.25-25 mg/kg, p.o.) showed a significant antinociceptive effect compared to the control. LPEE (25 and 50 mg/kg, p.o.), LPEF (50 and 100 mg/kg, p.o.) and MT (12.5 and 25 mg/kg, p.o.) reduced the glutamate-evoked nociceptive response. Treatment with naloxone, L-arginine and glibenclamide reversed the effect of LPEF in glutamate test.
  
  
  CONCLUSIONS
  These 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.
authors.affiliation: Medicinal Plants Research Center, Department of Chemistry, Federal University of Piauí, Av. Nossa Senhora de Fátima s/n, 64049-550 Teresina, Brazil.
authors.forename: M S
authors.initials: MS
authors.lastname: Brandão
authors.forename: S S
authors.initials: SS
authors.lastname: Pereira
authors.forename: D F
authors.initials: DF
authors.lastname: Lima
authors.forename: J P C
authors.initials: JP
authors.lastname: Oliveira
authors.forename: E L F
authors.initials: EL
authors.lastname: Ferreira
authors.forename: M H
authors.initials: MH
authors.lastname: Chaves
authors.forename: F R C
authors.initials: FR
authors.lastname: Almeida
mesh_terms: D019342:Acetic Acid; D059787:Acute Pain / Q000139:chemically induced / Q000188:drug therapy*; D000700:Analgesics / Q000494:pharmacology / Q000627:therapeutic use*; D000818:Animals; D001120:Arginine / Q000494:pharmacology; D001522:Behavior, Animal / Q000187:drug effects; D002211:Capsaicin; D004195:Disease Models, Animal; D005557:Formaldehyde; D018698:Glutamic Acid; D005905:Glyburide / Q000494:pharmacology; D031381:Lecythidaceae; D008297:Male; D051379:Mice; D009270:Naloxone / Q000494:pharmacology; D009292:Narcotic Antagonists / Q000494:pharmacology; D008517:Phytotherapy; D010936:Plant Extracts / Q000494:pharmacology / Q000627:therapeutic use*; D018515:Plant Leaves
chemical_list: D000700:Analgesics; D009292:Narcotic Antagonists; D010936:Plant Extracts; D005557:Formaldehyde; D009270:Naloxone; D018698:Glutamic Acid; D001120:Arginine; D019342:Acetic Acid; D002211:Capsaicin; D005905:Glyburide