EFFECTS OF CHOLECYSTOKININ-OCTAPEPTIDE AND BC-264, A POTENT AND SELECTIVE CCK-B AGONIST ON ASPARTATE AND GLUTAMATE RELEASE FROM RAT HIPPOCAMPAL SLICES

In rat hippocampal slices, BC 264 (0.1-1 mu M), a highly potent and se lective CCK-B agonist, was found to increase basal release of endogeno us glutamate and aspartate but not that of GABA. The natural peptide, cholecystokinin octapeptide (CCK8) at 1 mu M, induced the same effect. The selective CCK-B receptor antagonist, L-365,260, completely revers ed these responses, confirming that they are related to CCK-B receptor activation. In the absence of extracellular Ca2+, the increase in exc itatory amino acid release was completely abolished. In contrast to th e basal release, the potassium evoked release of aspartate and glutama te was not modified by BC 264.