DIRECT EVIDENCE FOR INCREASE IN EXCITATORY AMINO-ACIDS RELEASE DURINGMOSSY FIBER LTP IN RAT HIPPOCAMPAL SLICES AS REVEALED BY THE PATCH SENSOR METHODS

We had previously established a patch sensor system for detecting over flow of excitatory amino acids (EAA) from hippocampal slices induced b y a single electric stimulus. We performed simultaneous recordings of patch sensor current and whole-cell current in rat hippocampal slices. Tetanus of messy fibers produced long-term potentiation (LTP) of exci tatory postsynaptic current (EPSC) recorded from a CA3 pyramidal cell with an increase in single electric stimulus-evoked patch current ampl itude recorded with a patch sensor positioned in the stratum lucidum. In Schaffer collateral-CA1 synapses, however, LTP of EPSC was accompan ied by an increase in AMPA-evoked whole-cell current, but not with cha nge in patch current in the stratum radiatum. These results indicate t hat EAA release is increased during messy fiber LTP but not CA1 LTP. ( C) 1997 Elsevier Science Ireland Ltd.