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Fast synaptic transmission mediated by P2X receptors in CA3 pyramidal cells of rat hippocampal slice cultures
Author(s) -
Mori Masahiro,
Heuss Christian,
Gähwiler Beat H.,
Gerber Urs
Publication year - 2001
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 - 10.1111/j.1469-7793.2001.t01-1-00115.x
Subject(s) - neurotransmission , ionotropic effect , neuroscience , glutamate receptor , chemistry , metabotropic glutamate receptor , metabotropic receptor , glutamatergic , gabaergic , biophysics , biology , receptor , biochemistry , inhibitory postsynaptic potential
1 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. 2 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. 3 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.