Postsynaptic and extrasynaptic localization of Kv4.2 channels in the mouse hippocampal region, with special reference to targeted clustering at gabaergic synapses

S. Jinno, A. Jeromin, T. Kosaka

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Abstract

Voltage-dependent potassium (Kv) channels in the CNS are involved in regulation of subthreshold membrane potentials, and thus reception and integration of synaptic signals. Although such features are particularly important for induction of hippocampal synaptic plasticity, relatively little is known about their subcellular localization. Here we analyzed the detailed distribution of Kv4.2 potassium channels in the mouse hippocampal region using confocal and electron microscopy. At the light microscopic level, the Kv4.2 immunoreactivity occurred in a punctate fashion in the whole area of the hippocampal region. In the hippocampus proper, most of the Kv4.2-positive puncta were small, and they were abundant at the dendritic compartments of pyramidal neurons. High-resolution confocal microscopy revealed that there was no apparent association between Kv4.2-positive puncta with major synaptic markers, such as vesicular glutamate transporters and glutamic acid decarboxylase. In the subicular complex and dentate gyrus, we encountered large distinct Kv4.2-positive puncta at the perimeter of somata and proximal dendrites of principal cells. These puncta were often in contact with glutamic acid decarboxylase-positive boutons, but showed no apparent association with vesicular glutamate transporters. The glutamic acid decarboxylase-positive boutons apposing to Kv4.2-positive puncta were parvalbumin-positive. Quantitative image analysis showed that approximately half of Kv4.2-positive puncta were closely apposed to glutamic acid decarboxylase-positive boutons in the parasubiculum and dentate gyrus. Electron microscopic examination substantiated the presence of large Kv4.2-positive patches at postsynaptic sites of symmetric synapses and small patches at extrasynaptic sites. No presynaptic terminals were labeled. The present findings indicate targeted clustering of Kv4.2 potassium channels at postsynaptic sites of GABAergic synapses and extrasynaptic sites, and provide some key to understand their role in the hippocampal region.

Original languageEnglish
Pages (from-to)483-494
Number of pages12
JournalNeuroscience
Volume134
Issue number2
DOIs
Publication statusPublished - Aug 18 2005

Fingerprint

Glutamate Decarboxylase
Synapses
Shal Potassium Channels
Cluster Analysis
Vesicular Glutamate Transport Proteins
Dentate Gyrus
Confocal Microscopy
Voltage-Gated Potassium Channels
Parvalbumins
Neuronal Plasticity
Pyramidal Cells
Presynaptic Terminals
Carisoprodol
Dendrites
Membrane Potentials
Hippocampus
Electron Microscopy
Electrons
Light

All Science Journal Classification (ASJC) codes

  • Neuroscience(all)

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Postsynaptic and extrasynaptic localization of Kv4.2 channels in the mouse hippocampal region, with special reference to targeted clustering at gabaergic synapses. / Jinno, S.; Jeromin, A.; Kosaka, T.

In: Neuroscience, Vol. 134, No. 2, 18.08.2005, p. 483-494.

Research output: Contribution to journalArticle

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