Learning-specific decrease in synaptosomal ATP diphosphohydrolase activityfrom hippocampus and entorhinal cortex of adult rats

Considering the involvement of extracellular ATP in the memory formation, w e analyzed the effect of inhibitory avoidance training on ectonucleotidase activities in synaptosomes from hippocampus, entorhinal cortex and parietal cortex. ATP diphosphohydrolase activity presented a decrease (33%) in hipp ocampal synaptosomes of rats sacrificed 180 min after training. Our results also showed a decrease in synaptosomal ATP diphosphohydrolase (30% and 42% for ATP and ADP, respectively) in entorhinal cortex immediately after trai ning. These findings suggest an integrated action of ATP diphosphohydrolase from hippocampus and entorhinal cortex in the formation of inhibitory avoi dance memory. (C) 2000 Elsevier Science B.V. All rights reserved.