Repeated administration of antidepressants decreases field potentials in rat frontal cortex

The effects of repeated administration of a tricyclic antidepressant, imipramine, and a selective serotonin reuptake blocker, citalopram, for 14 days (10 mg/kg p.o., twice daily), were studied ex vivo in rat frontal cortex slices prepared 48 h after last dose of the drug. Treatment with both antidepressants resulted in a decrease in the amplitude of field potentials evoked in layer II/III by stimulation of underlying sites in layer V. The amplitude ratio of pharmacologically isolated N-methyl-D-aspartic acid (NMDA) to alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA)/kainate receptor-mediated components of the field potential was reduced. These results indicate that chronic treatment with imipramine or citalopram results in an attenuation of glutamatergic synaptic transmission in the cerebral cortex. (C) 2003 IBRO. Published by Elsevier Science Ltd. All rights reserved.