N-methyl-D-aspartate stimulates the release of dopamine from rat hippocampal slices

Rat hippocampal slices were loaded with [14C]dopamine (DA) and superfused continuously with oxygenated Mg2(+)-free Krebs-Henseleit solution. A 5-min pulse of 1 mM N-methyl-D-aspartate (NMDA) temporarily enhanced the basal release of DA by 30%. This effect was blocked by 50 microM D,L-2-amino-5-phosphonovalerate, a selective NMDA receptor antagonist, as well as by 0.5 microM tetrodotoxin. These results suggest that NMDA receptors on hippocampal interneurons may modulate the DA release. A possible link between the NMDA-induced release of DA and mechanisms enabling the maintenance of synaptic long-term potentiation in the hippocampus is discussed.