Inhibition of GABA release by presynaptic ionotropic GABA receptors in hippocampal CA3
Nikolai Axmacher1, Andreas Draguhn
1Johannes-Müller-Institut für Physiologie, Humboldt Universität Berlin, Tucholskystr. 2, 10117 Berlin, Germany.
Abstract:
Vesicular transmitter release can be regulated by transmitter-gated ion channels at presynaptic axon terminals. The central inhibitory transmitter GABA acts on such presynaptic ionotropic receptors in various cells, including inhibitory interneurons. Here we report that GABA-mediated postsynaptic inhibitory currents in CA3 pyramidal cells of rat hippocampal slices are suppressed by agonists of GABAA receptors. The effect is present for both stimulus-induced and miniature IPSCs, indicating a reduction in the probability of vesicular release by presynaptic, action-potential-independent mechanisms. We conclude that the release of GABA from hippocampal CA3 interneurons is regulated by a negative feedback via presynaptic ionotropic GABA autoreceptors.
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