Effects of clozapine, olanzapine and haloperidol on nitric oxide production by lipopolysaccharide-activated N9 cells

Prog Neuropsychopharmacol Biol Psychiatry. 2006 Dec 30;30(8):1523-8. doi: 10.1016/j.pnpbp.2006.05.006. Epub 2006 Jun 27.


Schizophrenia is a devastating illness of unknown etiology and the basis for its treatment rests in the symptomatic response to antipsychotics. It was found that some of the patients with schizophrenia elicited microglia activation. The present study used lipopolysaccharide (LPS)-activated mouse microglial cell line N9 as an in vitro model to mimic microglia activation seen in the patients with schizophrenia. The effects of clozapine, olanzapine and haloperidol on the release of nitric oxide (NO) by LPS-stimulated N9 cells were investigated. The results showed that olanzapine significantly inhibited NO release by LPS-stimulated N9 cells. Clozapine and haloperidol did not show significant effects on this model. The present study suggested that the inhibiting effect of olanzapine on the NO release by LPS-stimulated microglial cells might be a new mechanism through which olanzapine exhibits its therapeutic effect in the treatment of schizophrenia.

MeSH terms

  • Animals
  • Antipsychotic Agents / pharmacology
  • Benzodiazepines / therapeutic use
  • Cell Line
  • Cell Survival / drug effects
  • Clozapine / therapeutic use*
  • Haloperidol / pharmacology*
  • Lipopolysaccharides / pharmacology*
  • Mice
  • Microglia / cytology
  • Microglia / drug effects
  • Microglia / physiology*
  • Nitric Oxide / biosynthesis*
  • Nitric Oxide / metabolism
  • Nitrites / metabolism
  • Olanzapine


  • Antipsychotic Agents
  • Lipopolysaccharides
  • Nitrites
  • Benzodiazepines
  • Nitric Oxide
  • Clozapine
  • Haloperidol
  • Olanzapine