Differential release of d-[ 3H]aspartate and [ 14C]γ-aminobutyric acid following activation of commissural fibres in a longitudinal slice preparation of guinea pig hippocampus

Abstract

Low-stimulus frequencies released both d-[ 3H]aspartate and [ 14C]GABA in double labelling experiments after activation of the commissural fibres to stratum oriens in hippocampal slices. The stimulus-dependent release of [ 14C]GABA was highest at low stimulus frequencies (10 Hz) whereas at higher stimulus frequencies (30–50 Hz) it was almost abolished. All stimulus frequencies used released d-[ 3H]aspartate. The results indicate that activation of the commissural fibres in stratum oriens, using low stimulus frequencies, activates pyramidal cells which stimulate inhibitory neurones releasing GABA as a transmitter.