title: [The effect of formalin-induced pain on CCK in rat spinal cord neurons].
abstract: OBJECTIVE
  CCK is one of the strongest endogenous anti-opioid substances and suppresses morphine tolerance which results from long term use of morphine. This study explores the modulatory effect of CCK on pain formalin-induced.
  
  
  METHODS
  The effect of formalin-induced pain on CCK immunoreactivity in rat sensory neurons was observed through immunohistochemistry technique.
  
  
  RESULTS
  After 1 h of subcutaneous injection of formalin in one paw of rats, the number of positive neurons of CCK immunoreactivity in spinal cord neurons was obviously increased and greater than that of non-injection side (P <0.01). The semi-quantitative optical density average values of CCK immunoreactivity neurons were 0.397 +/- 0.014 and 0.295 +/- 0.007 in injection side and non-injection side respectively, the difference was obvious (P < 0.01). After 3 h of subcutaneous injection of formalin in one paw of rats, the semi-quantitative optical density average values of CCK immunoreactivity neurons were 0.366 +/- 0.009 and 0.303 +/- 0.005 in injection side and noninjection side respectively, the difference was significant (P < 0.01).
  
  
  CONCLUSIONS
  Formalin-induced pain can significantly change semi-quantitative optical density average value of CCK immunoractivity in spinal cord neurons, this indicates CCK participates in modulation of pain.
authors.affiliation: Department of Physiology, Shihezi University Medical College, Shihezi 832002, China.
authors.forename: Li
authors.initials: L
authors.lastname: Li
authors.forename: Hong-an
authors.initials: HA
authors.lastname: Li
authors.forename: Jin-fang
authors.initials: JF
authors.lastname: Jiang
authors.forename: Wei-hua
authors.initials: WH
authors.lastname: Liang
authors.forename: Jun-qiang
authors.initials: JQ
authors.lastname: Si
mesh_terms: D000818:Animals; D002766:Cholecystokinin / Q000378:metabolism / Q000502:physiology*; D005260:Female; D005557:Formaldehyde; D008297:Male; D009474:Neurons / Q000378:metabolism*; D010146:Pain / Q000139:chemically induced / Q000503:physiopathology*; D011897:Random Allocation; D051381:Rats; D017208:Rats, Wistar; D011949:Receptors, Cholecystokinin / Q000378:metabolism / Q000502:physiology; D013116:Spinal Cord / Q000378:metabolism* / Q000473:pathology
chemical_list: D011949:Receptors, Cholecystokinin; D005557:Formaldehyde; D002766:Cholecystokinin