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Involvement of post‐synaptic kainate receptors during synaptic transmission between unitary connections in rat neocortex
Author(s) -
Ali Afia B.
Publication year - 2003
Publication title -
european journal of neuroscience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.346
H-Index - 206
eISSN - 1460-9568
pISSN - 0953-816X
DOI - 10.1046/j.1460-9568.2003.02677.x
Subject(s) - kainate receptor , ampa receptor , excitatory postsynaptic potential , neurotransmission , neuroscience , neocortex , glutamate receptor , chemistry , kainic acid , receptor , glutamatergic , inhibitory postsynaptic potential , biophysics , biology , biochemistry
The properties of functional kainate receptor‐mediated EPSCs were studied in acute slices from 19–35‐day‐old rats. EPSCs elicited in pyramidal and fast‐spiking cells in layers 2/3 and 5 of the rat motor cortex by extracellular single shock stimulus in the presence of GYKI 53655 and D‐2‐amino‐5‐phosphopentanoic resulted in a residual current. This current was not enhanced by cyclothiazide but was blocked by 6‐cyano‐7‐nitroquinoxalin‐2,3‐dione and is thought to be mediated by kainate receptors. These kainate receptor‐mediated currents displayed a wide range of time courses depending on which pre‐synaptic fibres were activated. With paired recordings, unitary EPSCs elicited in pyramidal cells were almost totally blocked by GYKI 53655 and D‐2‐amino‐5‐phosphopentanoic. However, when L‐transpyrrolidine‐2,4‐dicarboxylate (PDC), a glutamate uptake blocker, was introduced in the bath, the amplitude of kainate receptor‐mediated currents, which is resistant to GYKI 53655 and D‐2‐amino‐5‐phosphopentanoic, was revealed. The rise and decay time constants of the kainate receptor‐mediated currents were identical to control EPSCs. PDC was not required to reveal the kainate receptor‐mediated currents elicited in fast‐spiking cells which also displayed similar rise and decay time constants to the control EPSCs. Excitatory input onto pyramidal and fast‐spiking cells in the neocortex mediated by kainate receptors contributed between 14 and 40% of the total control unitary EPSCs which displayed identical time courses to the AMPA receptor‐mediated component of the EPSCs. Post‐synaptic kainate receptors at connected pyramidal cell synapses may be located extra‐synaptically.