Methylglucamine orotate, a memory-improving drug, prolongs hippocampal long-term potentiation.

We showed earlier that the memory-improving substance, methylglucamine orotate, a precursor of pyrimidine nucleotide synthesis, improved memory retention and enhanced the postconditioning potentiation of field potentials in a special learning task. Since long-term potentiation (LTP) is frequently regarded as a mechanism of memory formation, we decided to test whether it can be influenced in a similar manner. The present study shows that the same dose of methylglucamine orotate (225 micrograms i.c.v.) prolongs LTP but has only a slight effect on the field potential recorded in the dentate gyrus. In controls, LTP of the population spike returned to 154% of the control value 24 h after tetanization and to 126% after 48 h. However, in drug treated animals LTP of the population spike remained at 246 and 216% of the control, respectively. The results support the assumption that LTP is at least a component of memory formation.