The NMDA receptor antagonist MK-801 blocks acquisition and extinction of conditioned hypoalgesic responses in the rat.

摘要: The role of the N-methyl-D-aspartate (NMDA) receptor in Pavlovian conditioning hypoalgesic responses hotplate apparatus was examined using non-competitive NMDA antagonist MK-801. Either MK-801 or saline were administered before training phase, test both, and disrupted acquisition extinction but not expression conditioned responses. All rats received counterbalanced injections both after therefore learning decrements could be attributed to a delayed, non-specific action drug. did augment paw-lick latencies on either days, indicating that its behavioural effects are due alterations nociceptive sensitivity motor performance. Similarly, MK-801's upon state-dependent generalization decrement impairments processing hot-plate cues during training, as displayed normal when tested with MK-801, MK-801-treated animals habituation novelty-induced hypoalgesia apparatus. These data suggest system is involved extinction, parallels antagonists long-term potentiation (LTP) vitro vivo. It plausible an endogenous NMDA-mediated form LTP plays vital storage aversive representations mediating