Sodium pump activity, amino acid transport and long-term memory

Long-term protein synthesis-dependent memory formation is shown to be inhibited by the non-metabolizable amino acid alpha-amino-isobutyrate (AIB) possibly through a process related to competition for uptake with amino acids necessary for protein synthesis specific to long-term memory. Unlike cycloheximide (CXM) which inhibits long-term memory by inhibiting ribosomal protein synthesis, AIB is non-effective when administered 10 min or more after learning, and its effect is overcome by the sodium pump stimulator diphenylhydantoin if the latter is administered 10 min or more after learning. Within the model of memory formation adopted in this paper it is postulated that the amino acids necessary for long-term memory protein synthesis are taken up by sodium pump activity in the first 10 min following learning, when formation of the preceding labile memory phase is occurring.