BLOCKERS OF NMDA RECEPTOR RESTORE PAIRED-PULSE INHIBITION IN THE RAT DENTATE GYRUS LESIONED BY PERFORANT PATH STIMULATION

The 'dormant basket cell' hypothesis postulates, that after status epi lepticus, inhibitory interneurons in the hippocampus are deafferented from their excitatory inputs. We provide evidence for active suppressi on of hippocampal inhibition. Status epilepticus-like perforant path s timulation induced loss of interneurons and loss of inhibition in the rat dentate gyrus. This loss was transiently reversed by antagonists a cting at three different sites of the N-methyl-d-aspartate (NMDA) rece ptor. Intrahippocampal administration of gamma-aminobutyric acid (GABA ) agonists, which were expected to increase inhibition, resulted in th e opposite effect. Although the substrate for the observed effects of pharmacological agents cannot be certainly confined to the 'dormant' b asket cell, they suggest the expression of hippocampal circuits that a ctively suppress inhibition through an NMDA synapse. (C) 1997 Elsevier Science Ireland Ltd.