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Early expression of AMPA receptors and lack of NMDA receptors in developing rat climbing fibre synapses
Author(s) -
Lachamp Philippe,
Balland Bénedicte,
Tell Fabien,
Baude Agnès,
Strube Caroline,
Crest Marcel,
Kessler JeanPierre
Publication year - 2005
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1113/jphysiol.2005.084517
Subject(s) - ampa receptor , long term depression , nmda receptor , silent synapse , neuroscience , glutamatergic , receptor , glutamate receptor , biology , ion channel linked receptors , excitatory postsynaptic potential , chemistry , microbiology and biotechnology , biochemistry , inhibitory postsynaptic potential
Whether nascent glutamatergic synapses acquire their AMPA receptors constitutively or via a regulated pathway triggered by pre‐existing NMDA receptor activation is still an open issue. Here, we provide evidence that some glutamatergic synapses develop without expressing NMDA receptors. Using immunocytochemistry, we showed that synapses between developing rat climbing fibres and Purkinje cells expressed GluR2‐containing AMPA receptors as soon as they were formed (i.e. on embryonic day 19) but never carried detectable NMDA receptors. This was confirmed by electrophysiological recordings. Excitatory synaptic currents were recorded in Purkinje cells as early as P0. However, no NMDA receptor‐mediated component was found in either spontaneous or evoked synaptic responses. In addition, we ruled out a possible role of extrasynaptic NMDA receptors by showing that AMPA receptor clustering at nascent climbing fibre synapses was not modified by chronic in utero NMDA receptor blockade.