title: Caspase activation in neuronal and glial apoptosis following spinal cord injury in mice.
abstract: The involvement of caspases in apoptosis after spinal cord injury (SCI) was investigated in adult mouse spinal cord after contusion. Sections of spinal cord were processed for staining 7 days after SCI with the fluorescent dye Hoechst 33342, terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end-labeling (TUNEL), and immunostaining with an antibody (CM1) recognizing activated caspase-3. Caspase-3- and caspase-8-like enzyme activities were measured colorimetrically at 8 hours to 7 days after SCI using the specific substrates Asp-Glu-Val-Asp-p-nitroanilide and Ile-Glu-Thr-Asp-p-nitroanilide, respectively. Hoechst 33342 staining showed small, bright areas in fragmented nuclei. Double labeling with TUNEL plus immunostaining with cell type-specific markers identified TUNEL-positive neurons stained by anti-neuronal nuclear protein/neurons antibody, and TUNEL-positive oligodendrocytes stained by anti-cyclic nucleotide 3'-phosphohydrolase antibody. Double labeling with CM1 and cell-type specific markers similarly identified CM1-positive neurons and oligodendrocytes. Caspase-8-like enzyme activity was increased significantly on days 3 and 7 (p < 0.01), whereas caspase-3-like activity increased on day 7 (p < 0.01). Intraventricular injection of a nonspecific tetrapeptide caspase inhibitor or a specific tetrapeptide inhibitor of caspase-3 just after SCI reduced enzyme activity at 7 days. Apoptotic cells were identified with TUNEL staining in both neurons and oligodendrocytes in mice after SCI, which also showed activated caspase-3. Increased caspase-3- and caspase-8-like activity was detected in the injured spinal cord on days 3 and 7. Caspase protease activities may be involved in delayed neuronal and glial apoptosis after SCI.
authors.affiliation: Department of Neurosurgery, Nagoya University School of Medicine, Nagoya, Japan.
authors.forename: Teruhide
authors.initials: T
authors.lastname: Takagi
authors.forename: Masakazu
authors.initials: M
authors.lastname: Takayasu
authors.forename: Masaaki
authors.initials: M
authors.lastname: Mizuno
authors.forename: Masayuki
authors.initials: M
authors.lastname: Yoshimoto
authors.forename: Jun
authors.initials: J
authors.lastname: Yoshida
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D020169:Caspases / Q000502:physiology*; D004195:Disease Models, Animal; D005260:Female; D051379:Mice; D008810:Mice, Inbred C57BL; D009457:Neuroglia / Q000502:physiology*; D009474:Neurons / Q000502:physiology*; D013119:Spinal Cord Injuries / Q000503:physiopathology*
chemical_list: D020169:Caspases