title: Anti-allodynic Efficacy of NMDA Antagonist Peptide and Noradrenaline Alone and in Combination in Rodent Neuropathic Pain Model.
abstract: BACKGROUND
  The present experiment was conducted to identify the cooperative effect of serine histogranin (SHG) and noradrenaline in alleviating peripheral neuropathic pain.
  
  
  METHODS
  Chronic constriction injury of the right sciatic nerve was used to induce chronic neuropathic pain. For drug delivery, a PE10 tube was inserted into the subarachnoid space. Acetone drops and a 44℃ water bath were used to evaluate the cold and heat allodynia, respectively. Placing and grasping reflexes were used to assess the locomotor system.
  
  
  RESULTS
  SHG at 0.5 and 1 µg significantly (P < 0.05) decreased the thermal allodynia. The cold allodynia was also significantly reduced by intrathecal injections of 0.5 (P < 0.05) and 1 µg (P < 0.001) of SHG. 1 µg of noradrenaline, but not 0.5 µg, significantly alleviated the cold (P < 0.01) and thermal (P < 0.05) allodynia. The ameliorating effect of noradrenaline or SHG disappeared when the two compounds were administrated in equal concentrations. A significant difference (P < 0.01 in the acetone and P < 0.05 in the heat) was observed in the groups under equal doses of the two compounds, with a lower effectiveness of the combination therapy.
  
  
  CONCLUSIONS
  Our findings suggest that the simultaneous administrations of noradrenaline and SHG do not result in synergistic analgesia, and combination therapy may not be a good approach to the treatment of chronic neuropathic pain syndrome.
authors: Physiology Research Center, Department of Physiology, Iran University of Medical Sciences, Tehran, Iran.
authors: Farinaz
authors: F
authors: Nasirinezhad
authors: Physiology Research Center, Department of Physiology, Iran University of Medical Sciences, Tehran, Iran.
authors: Marjan
authors: M
authors: Hosseini
authors: Department of Physiology, Ilam University of Medical Sciences, Ilam, Iran.
authors: Sajad
authors: S
authors: Salari
keywords: Antagonists and Inhibitors; N-Methyl-D-Aspartate; Neuropathic pain; Noradrenaline; Receptors