Current Pharmaceutical Design

William A. Banks  
VAPSHCS/GRECC S-182
Building 1, Room 810A
1600 S. Columbian Way
Seattle, WA 98108
USA

Back

Unraveling Monoamine Receptors Involved in the Action of Typical and Atypical Antipsychotics on Glutamatergic and Serotonergic Transmission in Prefrontal Cortex

Author(s): Xavier Lopez-Gil, Francesc Artigas, Albert Adell.

Abstract:

The systemic administration of noncompetitive N-methyl-D-aspartate (NMDA) receptor antagonists has been considered as a pharmacological model of schizophrenia. In the present work, we used in vivo microdialysis to examine: first, the effects of MK-801, on the efflux of glutamate and serotonin (5-HT) in the medial prefrontal cortex (mPFC) of the rat; second, whether the MK-801-induced changes in the cortical efflux of both transmitters could be blocked by atypical (clozapine and olanzapine) and classical (haloperidol and chlorpromazine) antipsychotic drugs given intra-mPFC; and third, the role of local blockade of dopamine D2/D3/D4, serotonin 5-HT2A and α1-adrenergic receptors as well as agonism at dopamine D1/D5 and 5-HT1A receptors in the mPFC on the increased efflux of glutamate and 5-HT elicited by MK-801. The four antipsychotic drugs blocked the MK-801-induced increase in glutamate, whereas only clozapine and olanzapine were able to block the increased efflux of 5-HT. Furthermore, M100907 (5-HT2A antagonist), BAY x 3702 (5-HT1A agonist) and prazosin (α1-adrenergic antagonist) blocked the MK-801-induced increase of 5-HT and glutamate in the mPFC. In contrast, raclopride (D2/D3 antagonist) and L-745,870 (D4 antagonist) were able to prevent the increased efflux of glutamate (but not that of 5-HT) elicited by MK-801. SKF-38393 (dopamine D1/D5 agonist) also prevented the MK-801-induced increase of glutamate in the mPFC, but the same effect on cortical 5-HT was reached only at the highest concentration tested. We suggest that the blockade of an exacerbated 5- HT release in the mPFC induced by NMDA antagonists can be a characteristic of atypical antipsychotic drugs. Moreover, we propose that D2/D3/D4 receptor antagonists would act predominantly on a subpopulation of GABAergic interneurons of the mPFC, thus enhancing cortical inhibition, which would prevent an excessive glutamatergic transmission. Dopamine D1/D5 agonists would further stimulate GABA release from other subpopulation of interneurons controlling cortical output to the dorsal raphe nucleus. Atypical antipsychotic drugs might further act upon 5-HT2A, 5-HT1A and α1-adrenoceptors present in pyramidal cells (including those projecting to the dorsal raphe nucleus), which would directly inhibit an excessive excitability of these cells.

Keywords: Serotonin, glutamate, prefrontal cortex, MK-801, dopamine D1/D2/D3/D4 receptors, 5-HT2A receptor, 5-HT1A receptor, α1- adrenoceptor

Order Reprints Order Eprints Rights & PermissionsPrintExport

Article Details

VOLUME: 16
ISSUE: 5
Year: 2010
Page: [502 - 515]
Pages: 14
DOI: 10.2174/138161210790361416
Price: $58