Clinical studies on the mechanism of action of clozapine: the dopamine-serotonin hypothesis of schizophrenia

Herbert Y. Meltzer*

*Corresponding author for this work

Research output: Contribution to journalArticle

547 Scopus citations

Abstract

Clozapine administration to schizophrenic patients was found to produce dopamine2 (D-2) and serotonin2 (5-HT2) receptor blockade, as evidenced by the ability to block the increases in growth hormone and cortisol secretion produced by apomorphine and MK-212, respectively, direct acting dopamine (DA) and 5-HT2 agonists. Clozapine did not increase plasma prolactin (PRL) levels nor did it block the apomorphine-induced decrease in plasma PRL concentration, as would be expected from a D-2 receptor antagonist. These PRL results are consistent with the observation that clozapine may increase DA release. Clozapine also decreased plasma tryptophan, plasma homovanillac acid (HVA) and basal plasma cortisol levels. Rodent studies suggest clozapine also increases 5-HT release. We hypothesize that antagonism of D-2 and 5-HT2 receptors and enhancement of DA and 5-HT release are critical elements in the action of clozapine to minimize both positive and negative symptoms without producing significant extrapyramidal symptoms or plasma PRL increases. It is proposed that schizophrenia may also involve a dysregulation of 5-HT2- and D-2-mediated neurotransmission, and that a more normal balance in serotonergic and dopaminergic neurotransmission is at least partially restored by clozapine.

Original languageEnglish (US)
Pages (from-to)S18-S27
JournalPsychopharmacology
Volume99
Issue number1 Supplement
DOIs
StatePublished - Mar 1 1989

Keywords

  • Clozapine
  • Cortisol
  • Dopamine
  • Serotonin
  • Tryptophan

ASJC Scopus subject areas

  • Pharmacology

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