Fast synaptic transmission mediated by P2X receptors in CA3 pyramidal cells of rat hippocampal slice cultures

A fast ATP-mediated synaptic current was identified in CA3 pyramidal cells in organotypic hippocampal slice cultures. In the presence of inhibitors for ionotropic glutamate and GABA receptors, extracellular stimulation in the pyramidal cell layer evoked fast synaptic currents that reversed near 0 mV...

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Bibliographic Details
Published in:The Journal of physiology 2001-08, Vol.535 (1), p.115-123
Main Authors: Mori, Masahiro, Heuss, Christian, Gähwiler, Beat H., Gerber, Urs
Format: Article
Language:English
Subjects:
Adenosine Triphosphate - metabolism
Animals
Electric Conductivity
Electric Stimulation
Hippocampus - cytology
Hippocampus - physiology
In Vitro Techniques
Original
Pyramidal Cells - physiology
Rats
Rats, Wistar
Receptors, Purinergic P2 - physiology
Receptors, Purinergic P2X
Synaptic Transmission - physiology
Time Factors
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Summary:A fast ATP-mediated synaptic current was identified in CA3 pyramidal cells in organotypic hippocampal slice cultures. In the presence of inhibitors for ionotropic glutamate and GABA receptors, extracellular stimulation in the pyramidal cell layer evoked fast synaptic currents that reversed near 0 mV, reflecting an increase in a non-selective cationic conductance. This response was mimicked by focal application of ATP. Antagonists of ionotropic P2X receptors reduced both synaptic and ATP-induced currents. Using a pharmacological approach, the source of synaptically released ATP was determined. Synaptic ATP responses were insensitive to presynaptic blockade of GABAergic transmission between interneurons and CA3 pyramidal cells with the μ-opioid receptor agonist D-Ala 2 ,MePhe 4 ,Met( O ) 5 -ol-enkephalin (FK33-824), but were blocked by adenosine, which inhibits glutamate release from synaptic terminals in the hippocampus. However, selective inhibition of mossy fibre glutamatergic transmission with the metabotropic glutamate receptor group II agonist (2 S ,2′ R ,3′ R )-2-(2′,3′-dicarboxycyclopropyl)glycine (DCG IV) did not affect the response. This result points to the associational fibres as the source of the ATP-mediated synaptic response. These results suggest that ATP, coreleased with glutamate, induces a synaptic response in CA3 pyramidal cells that is observed mainly under conditions of synchronous discharge from multiple presynaptic inputs.
ISSN:0022-3751
1469-7793
DOI:10.1111/j.1469-7793.2001.t01-1-00115.x