Indexed on: 01 Jan '93Published on: 01 Jan '93Published in: Molecular and chemical neuropathology / sponsored by the International Society for Neurochemistry and the World Federation of Neurology and research groups on neurochemistry and cerebrospinal fluid
The effects of NBQX and DNQX on synaptic transmission in rat hippocampal slice were investigated. Both agents produced dosedependent blockade of field potentials evoked by low frequency stimulation of Schaffer collateral-commissural fibers recorded in medium containing 4 mM Mg2+ (non-NMDA. mediated transmission), with half-maximal effects at about 0.15μM for NBQX and 1.0μM for DNQX. When the studies were conducted in Mg2+-free medium (predominantly NMDA mediated transmission), 100 μM NBQX failed to block transmission; however, the response could be completely blocked by the addition of 10μM of the competitive NMDA antagonist CPP. In contrast, 47 μM DNQX completely blocked secondary field potentials recorded in Mg2+-free medium and this effect could be reversed by the addition of 200 μM of the glycine agonist D-serine. Thus, NBQX exhibited selective blockade of non-NMDA mediated synaptic transmission whereas DNQX had effects at both non-NMDA and NMDA receptor sites, the latter effect via an interaction with the glycine site on the NMDA receptor complex.