Kainate receptors act as conditional amplifiers of spike transmission at hippocampal mossy fiber synapses.
Hippocampal mossy fiber (Mf) synapses are viewed as conditional detonators, assisting CA3 cells in complex network functions. By analyzing mice deficient for GluK2 (GluR6), GluK3 (GluR7) and GluK5 (KA2) genes we show that kainate receptors (KARs) play a crucial role in the control of synaptic integration and spike transmission efficacy at Mf synapses. We dissected out the role of the different KAR functions at Mf synapses and we show that presynaptic and postsynaptic KARs concur to amplify unitary Mf synaptic inputs to trigger spike discharge within a wide range of frequencies (from 1 to 50 Hz). Moreover, KARs strongly favor spike transmission in response to patterns of presynaptic activity mimicking in vivo dentate granule cell activity. By amplifying spike transmission, KARs also facilitate the induction of associative long-term potentiation in CA3. Hence the actions of KARs as amplifiers of spike transmission contribute largely to the "conditional detonator" function of Mf synapses and are likely important for spatial information processing.
Centre National de Recherche Scientifique (CNRS) Unité Mixte de Recherche 5091, Bordeaux Neuroscience Institute, University of Bordeaux, 33077 Bordeaux Cedex, France.
Shankar
S
Sachidhanandam
Christophe
C
Blanchet
Yannick
Y
Jeantet
Yoon H
YH
Cho
Christophe
C
Mulle
D000200:Action Potentials / Q000235:genetics / Q000502:physiology*; D000818:Animals; D019706:Excitatory Postsynaptic Potentials / Q000235:genetics / Q000502:physiology; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D019599:Mossy Fibers, Hippocampal / Q000502:physiology*; D021122:Protein Subunits / Q000172:deficiency / Q000235:genetics / Q000502:physiology; D018092:Kainic Acid Receptors / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D013569:Synapses / Q000235:genetics / Q000502:physiology*; D009435:Synaptic Transmission / Q000235:genetics / Q000502:physiology*
D021122:Protein Subunits; D018092:Kainic Acid Receptors