EFFECTS OF INTRASEPTAL INFUSIONS OF N-METHYL-D-ASPARTATE RECEPTOR LIGANDS ON MEMORY IN AN OBJECT RECOGNITION TASK IN RATS

The present study describes the effects of intraseptal microinjections of N-methyl-D-aspartate (NMDA) or AP5, an agonist and an antagonist o f the NMDA receptors, respectively, upon memory of rats. Animals were injected with the drug or vehicle immediately after the first exposure to two identical objects, and the duration of exploration of the fami liar and a new object were evaluated 45 min or 24 h later. Vehicle-tre ated rats explored the new object longer than the familiar object when the intertrial time was 45 min, indicating that they remembered the f amiliar object, but not when the intertrial time was 24 h. The differe nce of exploration time between the objects was increased by NMDA, but not by AP5, when the intertrial time was 24 h, and decreased by AP5 w hen the intertrial interval was 45 min. These results suggest that NMD A and AP5 improves and disrupts, respectively, the consolidation in a working memory task. (C) 1998 Published by Elsevier Science Ireland Lt d.