N-methyl-D-aspartate receptor antagonist MK-801 and spatial memory representation: working memory is impaired in an unfamiliar environment but not in a familiar environment.
Female Sprague-Dawley rats were injected with the noncompetitive N-methyl-D-aspartate (NMDA) antagonist MK-801 or saline 30 min before daily testing in spatial working memory (WM) and reference memory (RM) procedures in an 8-arm radial maze. MK-801 impaired RM and WM acquisition but not performance when rats were trained to criterion before drug administration. Neither a 2-hr nor a 4-hr delay between the first and last 2 correct WM choices impaired long-term WM. MK-801 impaired WM performance in trained rats only when rats were tested in a new environment. Thus, 2 mechanisms may be required for relational memory: an NMDA-dependent mechanism for acquiring long-term spatial representations and an NMDA-insensitive mechanism for operating on these stored representations.
Shapiro
M L
ML
Department of Psychology, McGill University, Montreal, Quebec, Canada.
O'Connor
C
C
D000818:Animals; D001070:Appetitive Behavior / Q000187:drug effects; D004193:Discrimination Learning / Q000187:drug effects*; D016291:Dizocilpine Maleate / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D005260:Female; D006624:Hippocampus / Q000187:drug effects*; D011939:Mental Recall / Q000187:drug effects*; D009949:Orientation / Q000187:drug effects*; D051381:Rats; D011919:Rats, Inbred Strains; D016194:Receptors, N-Methyl-D-Aspartate / Q000187:drug effects*; D012153:Retention, Psychology / Q000187:drug effects*; D012931:Social Environment
D016194:Receptors, N-Methyl-D-Aspartate; D016291:Dizocilpine Maleate