title: Induction of autophagy and autophagic cell death in damaged neural tissue after acute spinal cord injury in mice.
abstract: METHODS
  Expression of light chain 3 (LC3), a characteristic marker of autophagy, was examined by immunohistochemistry and Western blot using a spinal cord injury (SCI) model in mice. Electron microscopic analysis was also performed to examine the anatomic formation of autophagy and autophagic cell death in the injured spinal cord.
  
  
  OBJECTIVE
  To examine both biochemically and anatomically the activity of autophagy in the damaged neural tissue after SCI.
  
  
  BACKGROUND
  Autophagy is the bulk degradation of intracellular proteins and organelles, and it is involved in a number of diseases. Autophagy can lead to nonapoptotic programmed cell death, which is called autophagic cell death. Recent researches have revealed the increased expression of LC3 and the anatomic formation of autophagy and autophagic cell death in damaged tissues of various disease models. However, previous studies have focused on apoptotic process but not autophagic activity as mechanism of neural tissue damage after SCI. To date, there has been no study to examine the expression of LC3 and the anatomic formation of autophagy after SCI.
  
  
  METHODS
  The spinal cord was hemitransected at T10 in adult female C57BL/6J mice. The LC3 expression was examined by immunohistochemistry and Western blot. The anatomic formation of autophagic activity was investigated using electron microscopy.
  
  
  RESULTS
  Immunohistochemistry showed that the number of the LC3-positive cells significantly increased at the lesion site after hemisection. The increase of LC3-positive cells was observed from 4 hours and peaked at 3 days, and it lasted for at least 21 days after hemisection. The LC3-positive cells were observed in neurons, astrocytes, and oligodendrocytes. Western blot analysis demonstrated that the level of LC3-II protein expression significantly increased in the injured spinal cord. Electron microscopy showed the formation of autophagic vacuoles to increase in the damaged cells. Furthermore, the nuclei in the transferase-mediated dUTP nick end labeling-positive cells expressed LC3 were round, which is consistent with autophagic cell death, and they were neither shrunken nor fragmented as is observed in apoptotic nuclei.
  
  
  CONCLUSIONS
  This study suggested both biochemically and anatomically that autophagy was clearly activated and autophagic cell death was induced in the damaged neural tissue after SCI.
authors.affiliation: Department of Orthopaedic Surgery, Tohoku University School of Medicine, Sendai, Japan. kanno-h@isis.ocn.ne.jp
authors.forename: Haruo
authors.initials: H
authors.lastname: Kanno
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Ozawa
authors.forename: Akira
authors.initials: A
authors.lastname: Sekiguchi
authors.forename: Seiji
authors.initials: S
authors.lastname: Yamaya
authors.forename: Eiji
authors.initials: E
authors.lastname: Itoi
mesh_terms: D000208:Acute Disease; D000818:Animals; D017209:Apoptosis; D001343:Autophagy; D015415:Biomarkers / Q000378:metabolism; D015153:Blotting, Western; D004195:Disease Models, Animal; D005260:Female; D007150:Immunohistochemistry; D020287:In Situ Nick-End Labeling; D051379:Mice; D008810:Mice, Inbred C57BL; D008854:Microscopy, Electron; D008869:Microtubule-Associated Proteins / Q000378:metabolism; D009474:Neurons / Q000378:metabolism / Q000473:pathology* / Q000648:ultrastructure; D013116:Spinal Cord / Q000378:metabolism / Q000473:pathology* / Q000601:surgery / Q000648:ultrastructure; D013119:Spinal Cord Injuries / Q000378:metabolism / Q000473:pathology*; D013997:Time Factors
chemical_list: D015415:Biomarkers; C480860:Map1lc3b protein, mouse; D008869:Microtubule-Associated Proteins