title: Central Pain from Excitotoxic Spinal Cord Injury Induced by Intraspinal NMDA Injection: A Pilot Study.
abstract: BACKGROUND
  The pathophysiological and neurochemical changes following spinal injury are not yet elucidated. This study was designed to evaluate the morphological changes of the dorsal horn of the spinal cord and profiles of pain behaviors following intraspinal injection of NMDA in rats.
  
  
  METHODS
  RATS WERE RANDOMIZED INTO THREE GROUPS: a sham-operated control group and groups where the rats received 10 mM or 100 mM N-methyl-D-aspatate (NMDA) injected into their spinal dorsal horn. Following injection, hypersensitivity to cold and mechanical stimuli and excessive grooming behaviors were assessed serially for four weeks. Morphological changes of the spinal cord were evaluated four weeks after intraspinal injection.
  
  
  RESULTS
  Few animals in the NMDA groups developed hypersensitivity to cold and mechanical stimuli. The number of groomers and the severity of excessive grooming were significantly higher in the 100 mM NMDA group than those values of the control and 10 mM NMDA groups. The size of the neck region (lamina III-IV) was significantly smaller in the 100 mM NMDA group than in the control and 10 mM NMDA groups.
  
  
  CONCLUSIONS
  In conclusion, intraspinal injection of NMDA in rats leads to the pathological sequela in the spinal cord and to excessive grooming behavior. These results support the use of NMDA and excessive grooming behavior after excitotoxic SCI as a model to study chronic pain after SCI.
authors.affiliation: Department of Anesthesiology and Pain Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
authors.forename: Yeon Ju
authors.initials: YJ
authors.lastname: Leem
authors.forename: Jung Wha
authors.initials: JW
authors.lastname: Joh
authors.forename: Kyoung Woon
authors.initials: KW
authors.lastname: Joeng
authors.forename: Jeong Hun
authors.initials: JH
authors.lastname: Suh
authors.forename: Jin Woo
authors.initials: JW
authors.lastname: Shin
authors.forename: Jeong Gill
authors.initials: JG
authors.lastname: Leem