Clozapine protects adult neural stem cells from ketamine-induced cell death in correlation with decreased apoptosis and autophagy

Biosci Rep. 2020 Jan 31;40(1):BSR20193156. doi: 10.1042/BSR20193156.


Adult neurogenesis, the production of newborn neurons from neural stem cells (NSCs) has been suggested to be decreased in patients with schizophrenia. A similar finding was observed in an animal model of schizophrenia, as indicated by decreased bromodeoxyuridine (BrdU) labelling cells in response to a non-competitive N-methyl-d-aspartate (NMDA) receptor antagonist. The antipsychotic drug clozapine was shown to counteract the observed decrease in BrdU-labelled cells in hippocampal dentate gyrus (DG). However, phenotypic determination by immunohistochemistry analysis could not reveal whether BrdU-positive cells were indeed NSCs. Using a previously established cell model for analysing NSC protection in vitro, we investigated a protective effect of clozapine on NSCs. Primary NSCs were isolated from the mouse subventricular zone (SVZ), we show that clozapine had a NSC protective activity alone, as evident by employing an ATP cell viability assay. In contrast, haloperidol did not show any NSC protective properties. Subsequently, cells were exposed to the non-competitive NMDA-receptor antagonist ketamine. Clozapine, but not haloperidol, had a NSC protective/anti-apoptotic activity against ketamine-induced cytotoxicity. The observed NSC protective activity of clozapine was associated with increased expression of the anti-apoptotic marker Bcl-2, decreased expression of the pro-apoptotic cleaved form of caspase-3 and associated with decreased expression of the autophagosome marker 1A/1B-light chain 3 (LC3-II). Collectively, our findings suggest that clozapine may have a protective/anti-apoptotic effect on NSCs, supporting previous in vivo observations, indicating a neurogenesis-promoting activity for clozapine. If the data are further confirmed in vivo, the results may encourage an expanded use of clozapine to restore impaired neurogenesis in schizophrenia.

Keywords: autophagy; clozapine; fluoxetine; haloperidol; ketamine; neuroprotection.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult Stem Cells / drug effects*
  • Adult Stem Cells / metabolism
  • Adult Stem Cells / pathology
  • Animals
  • Apoptosis / drug effects*
  • Autophagy / drug effects*
  • Caspase 3 / metabolism
  • Cells, Cultured
  • Clozapine / pharmacology*
  • Excitatory Amino Acid Antagonists / toxicity*
  • Haloperidol / pharmacology
  • Ketamine / toxicity*
  • Lateral Ventricles / drug effects*
  • Lateral Ventricles / metabolism
  • Lateral Ventricles / pathology
  • Male
  • Mice, Inbred C57BL
  • Microtubule-Associated Proteins / metabolism
  • Neural Stem Cells / drug effects*
  • Neural Stem Cells / metabolism
  • Neural Stem Cells / pathology
  • Neurogenesis / drug effects
  • Neuroprotective Agents / pharmacology*
  • Proto-Oncogene Proteins c-bcl-2 / metabolism
  • Signal Transduction


  • Excitatory Amino Acid Antagonists
  • Map1lc3b protein, mouse
  • Microtubule-Associated Proteins
  • Neuroprotective Agents
  • Proto-Oncogene Proteins c-bcl-2
  • Bcl2 protein, mouse
  • Ketamine
  • Casp3 protein, mouse
  • Caspase 3
  • Clozapine
  • Haloperidol