title: Antinociceptive activity of Astragalus gummifer gum (gum tragacanth) through the adrenergic system: A in vivo study in mice.
abstract: BACKGROUND
  In Iranian traditional medicine, gum obtained from Astragalus gummifer and some other species of Astragalus was used as analgesic agent.
  
  
  OBJECTIVE
  In this study, we investigated the antinociceptive effect of several concentrations (125, 250, and 500 μg/kg body weight) of Astragalus gummifer gum (AGG) on thermal and acetic acid induced pain in mice.
  
  
  METHODS
  AGG was dissolved in distillated water and injected i.p to male mice 15 minute before the onset of experiment. Writhing and hot-plate tests were applied to study the analgesic effect of AGG and compared with that of diclofenac sodium (30 mg/kg, i.p.) or morphine (8 mg/kg, i.p). To investigate the mechanisms involved in antinociception, yohimbine, naloxone, glibenclamide, and theophylline were used in writhing test. These drugs were injected intraperitoneally 15 min before the administration of AGG. The number of writhes were counted in 30 minutes and analyzed.
  
  
  RESULTS
  AGG exhibited a significant antinociceptive effect and the most effective dose of AGG was 500 μg/kg. The most maximum possible effect (%MPE) was observed (117.4%) 15 min after drug administration. The %inhibition of acetic acid-induced writhing in AGG 125, 250 and 500 was 47%, 50% and 54% vs %15 of control and 66.3% of diclofenac sodium group. The antinociceptive effect induced by this gum in the writhing test was reversed by the systemic administration of yohimbine (α2-adrenergic antagonist), but naloxone, glibenclamide, and theophylline did not reverse this effect.
  
  
  CONCLUSIONS
  The findings of this study indicated that AGG induced its antinociceptive through the adrenergic system.
authors: Department of Physiology, Shahid Sadoghi University of Medical Sciences, Yazd, Iran.
authors: Seyyed Majid
authors: SM
authors: Bagheri
authors: Department of Biology, Azad Islamic University of Research Sciences, Shiraz, Iran.
authors: Leila
authors: L
authors: Keyhani
authors: Department of Biology, Azad Islamic University of Research Sciences, Shiraz, Iran.
authors: Mehrangiz
authors: M
authors: Heydari
authors: Neurobiomedical Research Center, Shahid Sadoghi University of Medical Sciences, Yazd, Iran.
authors: Mohammad Hossein
authors: MH
authors: Dashti-R
keywords: Astragalus gummifer; Astragalus gummifer gum; gum tragacanth; hot-plate; mechanism action; pain; writhing test