FAST INCREASES OF AMPA RECEPTOR SENSITIVITY FOLLOWING TETANUS-INDUCEDPOTENTIATION IN THE CA1 REGION OF THE RAT HIPPOCAMPUS

CHANGES in sensitivity of the alpha-amino-3-hydroxy-5-methyl-4-isoxazo le propionate (AMPA) subtype of glutamate receptors following the indu ction of long-term potentiation (LTP) were investigated in rat hippoca mpal slices. AMPA was ejected into the stratum radiatum of the hippoca mpal CA1 region by pressure ejection and the response recorded intrace llularly. Responses to AMPA exhibited a fast increase (2-3 min) follow ing LTP induction: the time course of this increase paralleled the pot entiation of the excitatory postsynaptic current (EPSC). In cases wher e there was no increase in the slope of intracellularly recorded EPSC following tetanization, no increase of the AMPA responses was observed . These results suggest that increases in postsynaptic AMPA sensitivit y can underlie short-term potentiation (STP) and thus, support a posts ynaptic locus for both STP and LTP.