Presynaptic kainate receptors are localized close to release sites in rat hippocampal synapses

The subsynaptic distribution of kainate receptors is still a matter of much debate given its importance to understand the way they influence neuronal communication. Here, we show that, in synapses of the rat hippocampus, presynaptic kainate receptors are localized within the presynaptic active zone...

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Bibliographic Details
Published in:Neurochemistry international 2005-10, Vol.47 (5), p.309-316
Main Authors: Pinheiro, P.S., Rodrigues, R.J., Rebola, N., Xapelli, S., Oliveira, C.R., Malva, J.O.
Format: Article
Language:English
Subjects:
Animals
Biological and medical sciences
Blotting, Western
Calcium
Calcium - metabolism
Calcium Channel Blockers - pharmacology
Calcium Signaling - physiology
Fundamental and applied biological sciences. Psychology
Glutamate release
Glutamic Acid - metabolism
Hippocampus
Hippocampus - metabolism
Hippocampus - ultrastructure
Immunohistochemistry
Kainic acid receptors
Male
Nerve Tissue Proteins - metabolism
Presynaptic
Rats
Rats, Wistar
Receptors, Kainic Acid - physiology
Receptors, Presynaptic - metabolism
Synaptosomes
Synaptosomes - metabolism
Synaptosomes - ultrastructure
Vertebrates: nervous system and sense organs
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Summary:The subsynaptic distribution of kainate receptors is still a matter of much debate given its importance to understand the way they influence neuronal communication. Here, we show that, in synapses of the rat hippocampus, presynaptic kainate receptors are localized within the presynaptic active zone close to neurotransmitter release sites. The activation of these receptors with low concentrations of agonists induces the release of [ 3H]glutamate in the absence of a depolarizing stimulus. Furthermore, this modulation of [ 3H]glutamate release by kainate is more efficient when compared with a KCl-evoked depolarization that causes a more than two-fold increase in the intra-terminal calcium concentration but no apparent release of [ 3H]glutamate, suggesting a direct receptor-mediated process. Using a selective synaptic fractionation technique that allows for a highly efficient separation of presynaptic, postsynaptic and non-synaptic proteins we confirmed that, presynaptically, kainate receptors are mainly localized within the active zone of hippocampal synapses where they are expected to be in a privileged position to modulate synaptic phenomena.
ISSN:0197-0186
1872-9754
DOI:10.1016/j.neuint.2005.05.007