title: Naloxone-resistant antinociceptive activity in the essential oil of Psidium pohlianum Berg.
abstract: The antinociceptive activity of the essential oil from leaves of Psidium pohlianum Berg (Myrtaceae) was evaluated in mice using three different nociceptive tests, namely, formalin, low temperature hot-plate (51 ± 1°C) and caudal compression method. Oral administration of Psidium oil (100, 200 and 400mg/kg) produced a dose-related significant antinociception in a hot-plate test, in a manner similar to morphine but appeared more persistant. Nociception induced by subplantar injection of formalin was also significantly attenuated by the essential oil at doses of 200 and 400 mg/kg. However, in a caudal compression test, a significant antinociceptive effect of the essential oil was observed only at 400 mg/kg. The antinociceptive effect of Psidium oil was not influenced by pretreatment of mice with naloxone (1 mg/kg, s. c.) in all the three tests. These observations suggest the presence of some volatile constituents in P. pohlianum essential oil capable of producing naloxone resistant antinociception in the mouse.
authors.affiliation: Departamento de Fisiologia e Farmacologia, Centro de Ciências da Saúde, Universidade Federal do Ceará, Cx. Postal 31 57, 60430-270 Fortaleza, CE, Brasil.
authors.forename: F A
authors.initials: FA
authors.lastname: Santos
authors.forename: V S
authors.initials: VS
authors.lastname: Rao
authors.forename: E R
authors.initials: ER
authors.lastname: Silveira