MK-801 induced retrieval, but not acquisition, deficits for passive avoidance conditioning

Two experiments using a state-dependent retention (SDR) design determined w hether MK-801 blocked the acquisition and retention of an avoidance respons e. In Experiments 1 and 2, rats were trained and tested 30 min after inject ions of either saline or MK-801 (0.05 and 0.10 mg/kg, respectively). Two mi nutes after training, subjects were immediately tested, and in both experim ents, the avoidance response was acquired. The 24-h retention tests for Exp eriment 1 revealed that the data marginally supported a SDR interpretation. In Experiment 2, the dose of MK-801 was increased to 0.10 mg/kg, and the r esults showed that NIK-801 rendered passive avoidance (PA) state-dependent. These experiments indicate that neither the 0.05 nor 0.10 mg/kg doses of M K-801 prevented acquisition of the avoidance response and that the latter d ose rendered memory for PA training state-dependent. It is suggested that d oses of MK-801 that did not impair PA learning can function as a cue state and influence expression of memory for PA. (C) 2001 Elsevier Science Inc. A ll rights reserved.