title: Antinociceptive effects of the essential oil of Croton nepetaefolius on mice.
abstract: Croton nepetaefolius Baill., is an aromatic plant native to the northeast of Brazil where it is extensively used in folk medicine as a sedative, orexigen and antispasmodic agent. In the present study the antinociceptive effects of the essential oil of C. nepetaefolius (EOCn), administered orally, were evaluated in male Swiss mice (20-25 g). In the acetic acid-induced writhing test, EOCn (100 and 300 mg/kg; N = 14 and N = 12, respectively) was effective at the highest dose. In the hot-plate test, EOCn at 30 and 300 mg/kg, but not at 3 mg/kg, significantly increased the latency at all observation times up to the 180th min (N = 12 for each dose). In the formalin test, EOCn significantly reduced paw licking in the second phase of the test at 100 mg/kg (N = 12), but decreased it in both phases at 300 mg/kg (N = 12). At 30 mg/kg, the effect of EOCn did not differ from control values in either phase of the formalin test (N = 6). Pretreatment with naloxone (5 mg/kg, ip) significantly reversed the analgesic effect of morphine (5 mg/kg, sc) on both phases, but not that of EOCn at 300 mg/kg (N = 6) on both phases of the formalin test. The data show that orally administered EOCn promotes a dose-dependent antinociceptive effect whose mechanisms remain to be elucidated.
authors.affiliation: Departamento de Ciéncias Fisiol gicas, Centro de Ciéncias da Saúde, Universidade Estadual do Ceará, Brasil.
authors.forename: A P V
authors.initials: AP
authors.lastname: Abdon
authors.forename: J H
authors.initials: JH
authors.lastname: Leal-Cardoso
authors.forename: A N
authors.initials: AN
authors.lastname: Coelho-de-Souza
authors.forename: S M
authors.initials: SM
authors.lastname: Morais
authors.forename: C F
authors.initials: CF
authors.lastname: Santos
mesh_terms: D000284:Administration, Oral; D000700:Analgesics / Q000627:therapeutic use*; D000818:Animals; D004353:Drug Evaluation, Preclinical; D019665:Euphorbiaceae; D008297:Male; D051379:Mice; D009822:Oils, Volatile / Q000627:therapeutic use*; D010147:Pain Measurement / Q000187:drug effects*; D010946:Plants, Medicinal
chemical_list: D000700:Analgesics; D009822:Oils, Volatile