Presynaptic kainate receptor activation is a novel mechanism for target cell-specific short-term facilitation at Schaffer collateral synapses.
Target cell-specific differences in short-term plasticity have been attributed to differences in the initial release probability of synapses. Using GIN (GFP-expressing inhibitory neurons) transgenic mice that express enhanced green fluorescent protein (EGFP) in a subset of interneurons containing somatostatin, we show that Schaffer collateral synapses onto the EGFP-expressing somatostatin interneurons in CA1 have very large short-term facilitation, even larger facilitation than onto pyramidal cells, in contrast to the majority of interneurons that have little or no facilitation. Using a combination of electrophysiological recordings and mathematical modeling, we show that the large short-term facilitation is caused both by a very low initial release probability and by synaptic activation of presynaptic kainate receptors that increase release probability on subsequent stimuli. Thus, we have discovered a novel mechanism for target cell-specific short-term plasticity at Schaffer collateral synapses in which the activation of presynaptic kainate receptors by synaptically released glutamate contributes to large short-term facilitation, enabling selective enhancement of the inputs to a subset of interneurons.
Sun
Hua Yu
HY
Department of Neurobiology, Civitan International Research Center, University of Alabama at Birmingham, Birmingham, Alabama 35294, USA.
Dobrunz
Lynn E
LE
D000818:Animals; D019706:Excitatory Postsynaptic Potentials / Q000502:physiology*; D006624:Hippocampus / Q000502:physiology; D066298:In Vitro Techniques; D008297:Male; D051379:Mice; D008822:Mice, Transgenic; D017966:Pyramidal Cells / Q000502:physiology; D011930:Reaction Time; D018092:Kainic Acid Receptors / Q000502:physiology*; D017661:Receptors, Presynaptic / Q000502:physiology*; D013569:Synapses / Q000502:physiology*; D009435:Synaptic Transmission / Q000502:physiology*
D018092:Kainic Acid Receptors; D017661:Receptors, Presynaptic