Anticonvulsants do not suppress long-term potentiation (LTP) in the rat hippocampus.

Long-term potentiation (LTP) of population spikes in the CA1 area of rat hippocampus was induced by tetanic stimulation of stratum radiatum in slices kept submerged in a perfusion chamber. Addition of the two antiepileptic drugs phenytoin or the diazepine midazolam to the medium did not significantly alter this phenomenon within 22 min after the tetanus. The early enhancement (post-tetanic potentiation, PTP) was reduced only by phenytoin. Therefore an interaction of these drugs with N-methyl-D-aspartate (NMDA) receptors and LTP induction is unlikely.