title: Ketamine induces apoptosis via the mitochondrial pathway in human lymphocytes and neuronal cells.
abstract: BACKGROUND
  Ketamine has been shown to have neurotoxic properties, when administered neuraxially. The mechanism of this local toxicity is still unknown. Therefore, we investigated the mechanism of cytotoxicity in different human cell lines in vitro.
  
  
  METHODS
  We incubated the following cell types for 24 h with increasing concentrations of S(+)-ketamine and racemic ketamine: (i) human Jurkat T-lymphoma cells overexpressing the antiapoptotic B-cell lymphoma 2 protein, (ii) cells deficient of caspase-9, caspase-8, or Fas-associated protein with death domain and parental cells, and (iii) neuroblastoma cells (SHEP). N-Methyl-d-aspartate (NMDA) receptors and caspase-3 cleavage were identified by immunoblotting. Cell viability and apoptotic cell death were evaluated flowcytometrically by Annexin V and 7-aminoactinomycin D double staining. Mitochondrial metabolic activity and caspase-3 activation were measured.
  
  
  RESULTS
  Ketamine, in a concentration-dependent manner, induced apoptosis in lymphocytes and neuroblastoma cell lines. Cell lines with alterations of the mitochondrial pathway of apoptosis were protected against ketamine-induced apoptosis, whereas alterations of the death receptor pathway did not reduce apoptosis. S(+)-Ketamine and racemic ketamine induced the same percentage of cell death in Jurkat cells, whereas in neuroblastoma cells, S(+)-ketamine was slightly less toxic.
  
  
  CONCLUSIONS
  Ketamine at millimolar concentrations induces apoptosis via the mitochondrial pathway, independent of death receptor signalling. At higher concentrations necrosis is the predominant mechanism. Less toxicity of S(+)-ketamine was observed in neuroblastoma cells, but this difference was minor and therefore unlikely to be mediated via the NMDA receptor.
authors.affiliation: Department of Anesthesiology, University of Düsseldorf, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Braun
authors.forename: N
authors.initials: N
authors.lastname: Gaza
authors.forename: R
authors.initials: R
authors.lastname: Werdehausen
authors.forename: H
authors.initials: H
authors.lastname: Hermanns
authors.forename: I
authors.initials: I
authors.lastname: Bauer
authors.forename: M E
authors.initials: ME
authors.lastname: Durieux
authors.forename: M W
authors.initials: MW
authors.lastname: Hollmann
authors.forename: M F
authors.initials: MF
authors.lastname: Stevens
mesh_terms: D000778:Anesthetics, Dissociative / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects* / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D006801:Humans; D019169:Jurkat Cells; D007649:Ketamine / Q000494:pharmacology*; D008928:Mitochondria / Q000187:drug effects* / Q000502:physiology; D009336:Necrosis; D009474:Neurons / Q000187:drug effects* / Q000473:pathology; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D013601:T-Lymphocytes / Q000187:drug effects* / Q000473:pathology; D014407:Tumor Cells, Cultured
chemical_list: D000778:Anesthetics, Dissociative; D007649:Ketamine