EFFECT OF ARACHIDONIC-ACID ON [H-3] D-ASPARTATE OUTFLOW IN THE RAT HIPPOCAMPUS

The aim of this study was to investigate the effect of arachidonic aci d on [H-3]d-aspartate outflow in rat hippocampus synaptosomes and slic es. Arachidonic acid 1) increased basal outflow of [H-3]d-aspartate in both synaptosomes and slices, and 2) increased K+-evoked overflow in slices but not in synaptosomes. The latter effect was dependent (at le ast in part) on arachidonic acid metabolism, most likely mediated by l ipo-oxygenase metabolites and flee radical production. It was prevente d by nordihydroguaiaretic acid but not by indomethacin, and was signif icantly reduced by free radical scavengers (superoxide-desmutase and c atalase). This effect was dependent upon stimulation since it could no t be observed after a continuous perfusion of arachidonic acid in the absence of stimulation. Furthermore, it was long-lasting since a 30 mi n perfusion of arachidonic acid was sufficient to exert a significant effect on a stimulation following termination of the application.