A COMPARISON OF (+ -)EPIBATIDINE WITH NMDA IN RELEASING [H-3] NORADRENALINE AND ADENOSINE FROM SLICES OF RAT HIPPOCAMPUS AND PARIETAL CORTEX/

We compared (+/-)epibatidine with N-methyl-D-aspartate (NMDA) in relea sing adenosine and [H-3]noradrenaline from slices of rat hippocampus a nd parietal cortex. (+/-)Epibatidine (0.1 mu M) released [H-3]noradren aline but not adenosine from hippocampal slices incubated either with or without extracellular Mg2+. In contrast, NMDA (300 mu M) released m uch more [H-3]noradrenaline and also adenosine from hippocampal slices incubated in medium lacking Mg2+. (+/-)Epibatidine released neither a denosine nor [H-3]noradrenaline from slices of rat parietal cortex, in contrast to NMDA which released both substances. These findings sugge st that those behavioral responses to (+/-)epibatidine that are mediat ed by noradrenaline may involve the hippocampus but not the parietal c ortex. Moreover, it seems unlikely that any of the behavioral effects of (+/-)epibatidine are mediated by adenosine release in either the pa rietal cortex or the hippocampus. (C) 1997 Elsevier Science Ireland Lt d.