Morphologically identified glycinergic synapses in the hippocampus.
Inhibitory transmission in the hippocampus is predominantly GABAergic, but electrophysiological data evidenced strychnine-sensitive glycine-induced currents. However, synaptic currents have not been reported. Here, we describe, for the first time, the presence of GlyR clusters in several areas of the hippocampus as well as in cultured hippocampal neurons. In contrast with spinal cord, hippocampal GlyRs contain alpha2 but no alpha1 subunit. Optical and electron microscopy indicates that GlyRs can be synaptic as well as extrasynaptic. Synaptic GlyRs were apposed to glycinergic boutons characterized by the expression of the vesicular and the plasma membrane transporters of glycine (VIAAT and GlyT2, respectively). Double labeling with calcium-binding proteins showed that GlyT2 could be detected in boutons innervating both excitatory cells (soma and dendrites) and interneurons. Finally, GlyR clusters could be detected at synaptic sites with the GABAA receptor gamma2 subunit and gephyrin, suggesting that mixed GABA/glycine synapses might exist in the hippocampus.
Danglot
Lydia
L
Laboratoire de Biologie Cellulaire de la Synapse N&P, Institut National de la Santé et de la Recherche Médicale U497, Ecole Normale Supérieure, 75005 Paris, France.
Rostaing
Philippe
P
Triller
Antoine
A
Bessis
Alain
A
D026905:Amino Acid Transport Systems / Q000378:metabolism; D026921:Amino Acid Transport Systems, Neutral / Q000378:metabolism; D000818:Animals; D002135:Calcium-Binding Proteins / Q000378:metabolism; D002352:Carrier Proteins / Q000378:metabolism; D002478:Cells, Cultured; D003712:Dendrites / Q000378:metabolism / Q000648:ultrastructure; D005998:Glycine / Q000378:metabolism*; D050487:Glycine Plasma Membrane Transport Proteins; D006624:Hippocampus / Q000378:metabolism* / Q000648:ultrastructure; D007150:Immunohistochemistry; D007395:Interneurons / Q000378:metabolism / Q000648:ultrastructure; D008565:Membrane Proteins / Q000378:metabolism; D046529:Microscopy, Electron, Transmission; D009433:Neural Inhibition / Q000502:physiology*; D017729:Presynaptic Terminals / Q000378:metabolism / Q000648:ultrastructure; D021122:Protein Subunits / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D011940:Receptor Aggregation / Q000502:physiology; D011963:Receptors, GABA-A / Q000378:metabolism; D013569:Synapses / Q000378:metabolism* / Q000648:ultrastructure; D013570:Synaptic Membranes / Q000378:metabolism / Q000648:ultrastructure; D009435:Synaptic Transmission / Q000502:physiology; D050495:Vesicular Inhibitory Amino Acid Transport Proteins; D033921:Vesicular Transport Proteins / Q000378:metabolism
D026905:Amino Acid Transport Systems; D026921:Amino Acid Transport Systems, Neutral; D002135:Calcium-Binding Proteins; D002352:Carrier Proteins; D050487:Glycine Plasma Membrane Transport Proteins; D008565:Membrane Proteins; D021122:Protein Subunits; D011963:Receptors, GABA-A; C118623:Slc32a1 protein, rat; C493269:Slc6a5 protein, rat; D050495:Vesicular Inhibitory Amino Acid Transport Proteins; D033921:Vesicular Transport Proteins; C073441:gephyrin; D005998:Glycine