title: Functional involvement of the lumbar spinal cord after contusion to T8 spinal segment of the rat.
abstract: OBJECTIVE
  To evaluate the effects on locomotion and lumbar motoneuron function after a contusion to the midthoracic spinal cord of the rat.
  
  
  METHODS
  Five animals received a moderate contusion on T8, and over 28 days postoperation (dpo) locomotion and motor electrophysiological outcome were compared with five sham-operated animals.
  
  
  RESULTS
  At 28 dpo, the contused animals supported their body weight (BBB score =11.5 ± 0.5) and stepped uncoordinatedly. Motor evoked potentials recorded in the tibialis anterior (TA) and plantar muscles (PL), and longitudinal interlimb reflexes recorded in the TA muscles were abolished. The M wave recorded in the TA showed a decrease in amplitude by 7 dpo, which remained invariable until the end of the evaluation (88 ± 3% of {preoperative} values), whereas in the PL muscle it was not affected. Injured animals presented hyperreflexia, as shown by an increased H/M ratio. Histological analysis showed similar number of retrogradely traced TA motoneurons between groups, and that contused animals presented hypertrophied astrocytes in the most rostral but not caudal segments of the lumbar enlargement.
  
  
  CONCLUSIONS
  These results indicate that after contusion to the thoracic spinal cord, the lumbar segments undergo structural and functional changes, following a rostro-caudal gradient extension.
authors.affiliation: Group of Neuroplasticity and Regeneration, Institute of Neurosciences and Department of Cell Biology, Physiology and Immunology, Universitat Autònoma de Barcelona, E-08193 Bellaterra, Spain. guillermo284@googlemail.com
authors.forename: Guillermo
authors.initials: G
authors.lastname: García-Alías
authors.forename: Abel
authors.initials: A
authors.lastname: Torres-Espín
authors.forename: Carolina
authors.initials: C
authors.lastname: Vallejo
authors.forename: Xavier
authors.initials: X
authors.lastname: Navarro
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D001253:Astrocytes / Q000473:pathology; D019054:Evoked Potentials, Motor / Q000502:physiology; D005260:Female; D007150:Immunohistochemistry; D008159:Lumbar Vertebrae / Q000473:pathology / Q000503:physiopathology; D009043:Motor Activity / Q000502:physiology*; D009046:Motor Neurons / Q000473:pathology / Q000502:physiology*; D009431:Neural Conduction / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013116:Spinal Cord / Q000473:pathology / Q000503:physiopathology*; D013119:Spinal Cord Injuries / Q000473:pathology / Q000503:physiopathology*; D013904:Thoracic Vertebrae / Q000293:injuries / Q000473:pathology