The process of learning, MK-801-induced amnesia, and its prevention mediated by the investigated ligands were cGMP-dependent, but the changes in the expression of GluN2B-NMDA subunits were not noticed, suggesting that the procedure and pharmacological manipulations putatively affected the glutamate–NO–cGMP axis and subsequent LTP, changing NMDA receptor susceptibility and functionality, but not density. This evidence concerns the gene GRIN2B and amnesia.