Research article summary (published 29 Jun 2002):

AMPA and NMDA currents show different short-term depression in the dorsal lateral geniculate nucleus of the rat.

Full Abstract

Paired-pulse depression was studied at the glutamatergic synapse between retinal afferents and thalamocortical cells in the rat dorsal lateral geniculate nucleus. The main objective of this study was to examine the contributions of the pre- and postsynaptic sites to this depression by comparing AMPA- and NMDA-receptor-mediated responses. Equal depression of the two receptor components would indicate involvement of presynaptic mechanisms, while differences in depression would indicate involvement of postsynaptic mechanisms. Pharmacologically isolated AMPA- and NMDA-receptor-mediated currents were recorded using the whole-cell patch-clamp technique in acute thalamic slices. Both the AMPA and the NMDA components showed pronounced depression when retinal afferents were activated by paired pulses. The depression decayed within 5 s. The AMPA component was more strongly depressed than the NMDA component at paired-pulse intervals ranging from 20 to 200 ms, suggesting the involvement of postsynaptic mechanisms. For intervals of 500 ms and longer, the depression of the two components was identical, suggesting the involvement of purely presynaptic mechanisms. The degree of depression measured without the use of pharmacological tools produced similar results, thus excluding the involvement of presynaptic ionotropic glutamate receptors. Cyclothiazide, a blocker of AMPA-receptor desensitisation, reduced the difference in depression between the two components, suggesting that desensitisation of the AMPA receptors is a postsynaptic mechanism that contributes to the difference in depression between the AMPA and the NMDA components.

Author information

Author/s: Kielland, Anders (A); Heggelund, Paul (P);

Affiliation: University of Oslo, Institute of Basic Medical Sciences, Department of Physiology, P.O. Box 1103-Blindern, N-0317 Oslo, Norway. anders.kielland(-atsign-)basalmed.uio.no

Journal and publication information

Publication Type: In Vitro; Journal Article

Journal: The Journal of physiology (J Physiol), published in England. (Language: eng)

Reference: 2002-Jul; vol 542 (issue Pt 1) : pp 99-106

Dates: Created 2002/07/03; Completed 2003/01/28; Revised 2008/11/20;

PMID: 12096054, status: MEDLINE (last retrieved date: 2/18/2009)

Sourced from the National Library of Medicine. Abstract text and other information may be subject to copyright.

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MeSH headings (categories)

This article was linked to the MeSH Headings (categories) shown below.

Animals Benzothiadiazines - pharmacology Cerebral Cortex - cytology; drug effects; physiology Electric Stimulation Excitatory Postsynaptic Potentials - drug effects; physiology Geniculate Bodies - drug effects; metabolism Glutamic Acid - metabolism Kinetics Magnesium - pharmacology

Neurons, Afferent - drug effects; physiology Rats Rats, Wistar Receptors, AMPA - drug effects; metabolism Receptors, N-Methyl-D-Aspartate - drug effects; metabolism Receptors, Presynaptic - drug effects; metabolism Retina - cytology; drug effects Synapses - drug effects; metabolism Thalamus - cytology; drug effects; physiology

Note: Bold headings indicate primary MeSH headings or qualifiers.

Associated Chemicals: Benzothiadiazines (0) ; Receptors, AMPA (0) ; Receptors, N-Methyl-D-Aspartate (0) ; Receptors, Presynaptic (0) ; cyclothiazide (2259-96-3) ; Glutamic Acid (56-86-0) ; Magnesium (7439-95-4)

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