title: Study the antinociceptive effect of intracerebroventricular injection of aqueous extract of origanum vulgare leaves in rat: possible involvement of opioid system.
abstract: OBJECTIVE
  The aim of study was to investigate the antinociceptive effect of intracerebroventricular (ICV) microinjection of Origanum vulgare (ORG) extract and possible involvement of opioid receptors.
  
  
  METHODS
  Cannula was inserted into left ventricle of male rats. Five days after surgery Tail Flick Latency (TFL) was measured after ICV microinjection of, ORG (1, 3 and 6 µg / rat). Effective dose of ORG was injected ICV in concomitant with morphine (2 mg/kg, IP), naloxone (2 mg / kg, IP) and saline (0.5 µl/rat) and TFL was recorded.
  
  
  RESULTS
  The co- administration of ORG extract with morphine showed a significant increase in TFL and naloxone, pretreatment significantly inhibited the antinociceptive activity of ORG and morphine.
  
  
  CONCLUSIONS
  The aqueous extract of ORG possesses antinociceptive activities in the tail-flick test in a dose dependent manner. ORG - induced antinociception may have been mediated by opioid systems.
authors.affiliation: Neuroscience Research Center and Department of Physiology, Faculty of Medicine, Kerman University of Medical Sciences, Kerman, Iran.
authors.forename: Yasaman
authors.initials: Y
authors.lastname: Pahlavan
authors.affiliation: Neuroscience Research Center and Department of Physiology, Faculty of Medicine, Kerman University of Medical Sciences, Kerman, Iran.
authors.forename: Gholamreza
authors.initials: G
authors.lastname: Sepehri
authors.affiliation: Neuroscience Research Center and Department of Physiology, Faculty of Medicine, Kerman University of Medical Sciences, Kerman, Iran.
authors.forename: Vahid
authors.initials: V
authors.lastname: Sheibani
authors.affiliation: Neuroscience Research Center and Department of Physiology, Faculty of Medicine, Kerman University of Medical Sciences, Kerman, Iran ; Department of Physiology, Faculty of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
authors.forename: Mohammadreza
authors.initials: M
authors.lastname: Afarinesh Khaki
authors.affiliation: Departments of Physiology, Faculty of Medicine, Tabriz University of Medical Sciences, Tabriz, Iran.
authors.forename: Morteza
authors.initials: M
authors.lastname: Gojazadeh
authors.affiliation: Faculty of Medicine, Tabriz University of Medical Sciences, Tabriz, Iran.
authors.forename: Bahare
authors.initials: B
authors.lastname: Pahlavan
authors.affiliation: Faculty of Medicine, Ardabil Azad University of Medical Sciences, Ardabil, Iran.
authors.forename: Fereshteh
authors.initials: F
authors.lastname: Pahlavan
keywords: Intracerebroventricular; Origanum vulgare; Pain; Rat; Tail-flick test