BLOCKADE OF SPONTANEOUS POSTTRAINING PERFORMANCE IMPROVEMENT IN MICE BY NMDA ANTAGONISTS

We investigated the effects of immediate post training systemic admini stration of gamma-L-glutamyl-L-aspartate (gamma-LGLA) and 3-(2-carboxy piperazine-4-yl)-propyl-1-ph (CPP), antagonists at the N-merhyl-D-aspa rtate receptor, in a lever-press task in two inbred strains of mice. W hen retention performance was tested in control animals 24 h after par tial acquisition of the task, BALB/c mice exhibited a spontaneous perf ormance improvement whereas C57BL/6J mice did not. gamma-LGLA at doses of 2.5 and 25 mu mol/kg and CPP at doses ranging between 0.025 and 2. 5 mu mol/kg blocked the spontaneous performance improvement found in B ALB/c mice but had no apparent effects on the retention performance of C57BL/6J mice. These data suggest that retention impairment induced b y CPP and gamma-LGLA in BALB/c mice results from an interference with posttraining memory processes. (C) 1997 Elsevier Science Inc.