Evaluation of the role of NMDA receptor function in antidepressant-like activity. A new study with citalopram and fluoxetine in the forced swim test in mice

BackgroundThe NMDA/glutamate receptors are involved in the mechanism of antidepressant activity.MethodsThe present study was designed to investigate the effect of NMDA receptor ligands (agonists and antagonists of glutamate sites) on the antidepressant-like activity of selective serotonin reuptake inhibitors (SSRIs), citalopram and fluoxetine, in the forced swim test in mice.ResultsThe antidepressant activity (reduction in immobility time) of citalopram but not of fluoxetine was antagonized by N-methyl-d-aspartate acid and enhanced by CGP37849 (antagonist of the NMDA receptor).ConclusionsThe present literature data indicate that the antidepressant-like activity of conventional antidepressants is generally affected by the NMDA receptor, although by modulation from different sites of the complex. Thus, it supports the issue of the ability of NMDA receptor antagonists to enhance the antidepressant action in human depression.