Synaptic transmission onto hippocampal glial cells with hGFAP promoter activity.
Glial cells increasingly gain importance as part of the brain's communication network. Using transgenic mice expressing green fluorescent protein (EGFP) under the control of the human GFAP promoter, we tested for synaptic input to identified glial cells in the hippocampus. Electron microscopic inspection identified synapse-like structures with EGFP-positive postsynaptic compartments. Sub-threshold stimulation to Schaffer collaterals resulted in stimulus-correlated, postsynaptic responses in a subpopulation of EGFP-positive cells studied with the patch-clamp technique in acute slices. This cell population can be recognized by its distinct morphology and has been termed GluR cells in a preceding study. These cells are distinct from the classical astrocytes due to their antigen profile and functional properties, but also lack characteristic features of oligodendrocytes or neurons. GluR cells also received spontaneous synaptic input. Stimulus-correlated and spontaneous responses were quantitatively analysed by ascertaining amplitude distributions, failure rates, kinetics as well as pharmacological properties. The data demonstrate that GABAergic and glutamatergic neurons directly synapse onto GluR cells and suggest a low number of neuronal release sites. These data demonstrate that a distinct type of glial cells is integrated into the synaptic circuit of the hippocampus, extending the finding that synapse-based brain information processing is not a property exclusive to neurons.
Jabs
Ronald
R
Experimental Neurobiology, Department of Neurosurgery, University of Bonn, Sigmund-Freud-Str. 25, 53105 Bonn, Germany. ronald.jabs@ukb.uni-bonn.de
Pivneva
Tatjana
T
Hüttmann
Kerstin
K
Wyczynski
Alexandra
A
Nolte
Christiane
C
Kettenmann
Helmut
H
Steinhäuser
Christian
C
D000818:Animals; D002450:Cell Communication / Q000502:physiology*; D048430:Cell Shape / Q000502:physiology; D004558:Electric Stimulation; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D019706:Excitatory Postsynaptic Potentials / Q000502:physiology; D018756:GABA Antagonists / Q000494:pharmacology; D005904:Glial Fibrillary Acidic Protein / Q000235:genetics / Q000378:metabolism*; D018698:Glutamic Acid / Q000378:metabolism; D049452:Green Fluorescent Proteins; D006624:Hippocampus / Q000378:metabolism* / Q000648:ultrastructure; D006801:Humans; D007150:Immunohistochemistry; D051379:Mice; D008822:Mice, Transgenic; D046529:Microscopy, Electron, Transmission; D009457:Neuroglia / Q000378:metabolism* / Q000648:ultrastructure; D009924:Organ Culture Techniques; D018408:Patch-Clamp Techniques; D017729:Presynaptic Terminals / Q000378:metabolism* / Q000648:ultrastructure; D011401:Promoter Regions, Genetic / Q000235:genetics; D017470:Receptors, Glutamate / Q000378:metabolism; D011993:Recombinant Fusion Proteins; D009435:Synaptic Transmission / Q000502:physiology*; D005680:gamma-Aminobutyric Acid / Q000378:metabolism
D018691:Excitatory Amino Acid Antagonists; D018756:GABA Antagonists; D005904:Glial Fibrillary Acidic Protein; D017470:Receptors, Glutamate; D011993:Recombinant Fusion Proteins; D049452:Green Fluorescent Proteins; D018698:Glutamic Acid; D005680:gamma-Aminobutyric Acid