Dendritic excitation by glutamate in CA1 hippocampal cells.
In order to reveal properties and effects of glutamate excitation, CA1 pyramidal cells in rat hippocampal slices were impaled and responses to iontophoresis of glutamate onto sensitive spots in the dendrites were analyzed. The glutamate-elicited response consisted of a steady depolarization; its amplitude was dose-dependent. The cellular response to repeated applications of glutamate showed a striking degree of stability. Both dendritic and somatic depolarization, induced by glutamate and current, respectively, elicited similar discharge patterns. The sensitivity to glutamate was highly localized, corresponding to the dendritic tree of a given cell. Short, repeated glutamate pulses did not interfere with an orthodromic test response, whereas longer glutamate ejections often depressed the EPSP. Combined temporal and spatial pairing of glutamate and orthodromic activation was followed by a lasting increase in synaptic efficiency, similar to LTP.
Hvalby
O
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Institute of Neurophysiology, University of Oslo, Norway.
D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D004558:Electric Stimulation; D005971:Glutamates / Q000494:pharmacology*; D018698:Glutamic Acid; D006624:Hippocampus / Q000187:drug effects / Q000502:physiology*; D066298:In Vitro Techniques; D018377:Neurotransmitter Agents / Q000494:pharmacology*; D051381:Rats
D005971:Glutamates; D018377:Neurotransmitter Agents; D018698:Glutamic Acid