FACILITATION OF THE INDUCTION OF LONG-TERM POTENTIATION BY GABA-B RECEPTORS

Long-term potentiation (LTP), an in vitro model of learning, was induced in hippocampal slices by 5-hertz stimulation. During induction, gamma-aminobutyric acid A (GABA(A)) inhibition decreased, causing the N-methyl-D-aspartate receptor-mediated excitation to increase. 2-OH Saclofen, a GABA(B) receptor antagonist, prevented the reduction of inhibition, the increase of excitation, and the induction of LTP. Therefore, disinhibition caused by GABA(B) receptors is required for induction of LTP by 5-hertz stimulation. GABA(B) receptor modulation of synaptic plasticity occurs at frequencies in the range of the endogenous hippocampal theta rhythm, which has been shown to modulate LTP in vivo.