title: The Effect of Acute Intra Locus Coeruleus (LC) Microinfusion of Bupropion on Formalin-Induced Pain Behavior in Rat.
abstract: BACKGROUND
  Inflammatory pain is a common sign of chronic diseases. Some brain regions such as locus coeruleus (LC) of the brainstem nor-epinephrine (NE) system have a key role in The mechanisms of the pain modulation and dependence. Bupropion synthesized as an antidepressant, but it is using for smoke cessation. It can change morphine withdrawal signs such as pain related behaviors. This study tested the acute effect of intra-LC microinfusion of bupropion on the formalin-induced pain behavior in rats.
  
  
  METHODS
  Wistar male rats were divided into 6 groups (control-naïve, control-operated, shamoperated, and 3 treated groups with 10(-2), 10(-3), 10(-4) mol/µl intra-LC of bupropion). The injection guide cannulae were implanted into LC nuclei bilaterally by stereotaxic coordinated surgery under sterile condition. The sham group received normal saline as drug vehicle but control groups had no intra-LC injections. Formalin (50 µl, 2.5%) was injected subcutaneously in plantar region of the right hindpaw in all animals (30 min after drug administration in treated animals). Nociceptive signs were observed continuously and registered on-line each minute. Common pain scoring was used for pain assessment.
  
  
  RESULTS
  The analysis of data by one-way ANOVA showed that bupropion can reduce pain behavior scores significantly. Bupropion reduced total pain score in the phase 01 (60%) and phase 02 (52%) of maximal behavior compared to the sham group, dose dependently and significantly. The pain scores of controls and sham groups had no significant difference.
  
  
  CONCLUSIONS
  The results showed that bupropion has analgesic effects on LC neurons and can alter the neurochemical involvement of LC in pain process. Bupropion has different and significant effect on early and late phases of formalin test.
authors.affiliation: Department of Biology, Payame Noor University, Tehran, Iran.
authors.forename: Marzieh
authors.initials: M
authors.lastname: Jahanbani
authors.affiliation: Department of Biology, Payame Noor University, Tehran, Iran.
authors.forename: Sima
authors.initials: S
authors.lastname: Nasri
authors.affiliation: Neurophysiology Research Center, Urmia University of Medical Sciences, Urmia, Iran ; Department of Physiology, Faculty of Medicine, Urmia University of Medical Sciences, Urmia, Iran.
authors.forename: Firouz Ghaderi
authors.initials: FG
authors.lastname: Pakdel
authors.affiliation: Department of Histology & Embryology, School of Medicine, Dokuz EyluL University (DEU).
authors.forename: Ulker
authors.initials: U
authors.lastname: Cankurt
authors.affiliation: Neuroscience Research Center, Tabriz University of Medical Sciences, Tabriz, Iran.
authors.forename: Parviz
authors.initials: P
authors.lastname: Shahabi
authors.affiliation: Department of Physiology, Faculty of Medicine, Urmia University of Medical Sciences, Urmia, Iran.
authors.forename: Sanaz
authors.initials: S
authors.lastname: Amirabadi
authors.affiliation: Pakdel Research Lab, Urmia University of Medical Sciences, Urmia, Iran.
authors.forename: Somayyeh
authors.initials: S
authors.lastname: Naderi
authors.affiliation: Department of Histology & Embryology, School of Medicine, Dokuz EyluL University (DEU).
authors.forename: Mostafa Ashrafi
authors.initials: MA
authors.lastname: Osalou
keywords: Analgesia; Antidepressant; Bupropion; Formalin test; Locus Coeruleus; Pain; Rat