Input-specific distribution of A-type potassium channels in the thalamus.
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1
Department of Cellular and Network Neurobiology, Institute of Experimental Medicine, Hungary
Potassium channels formed by Kv4.2 and Kv4.3 subunits are responsible for a transient K+ current, the A-current in the brain, playing an important role in the integrative properties of dendrites. In the present study the so far unknown thalamic distribution of these subunits were studied. Kv4.2/Kv4.3 subunits formed strongly immunoreactive clusters on proximal dendrites of relay cells with largest accumulation in spine-like dendritic appendages in the ventral posteromedial nucleus (VPM) but not in the posterior nucleus (Po) or in the ventrolateral part of VPM (VPMvl). Double immunostaining with a marker for sensory afferents and either Kv subunits revealed at light- and electron microscopic level that Kv-clusters are present almost exclusively postsynaptic to large subcortical terminals and almost all of these terminals faced Kv-rich dendritic segments in the VPM. In the proximal dendrites of VPM the density of Kv immunogold labeling was 20 times higher on the membrane surfaces covered by sensory afferents compared to surfaces free of the input. During ontogeny Kv4.2/4.3-clusters developed in line with the ascending sensory pathway, were absent at P0-P5 but were fully developed at P24. Following lesion of the PrV, clusters selectively disappeared postsynaptic to degenerating terminals but were unaffected in dendrites contacted by intact terminals. Our data demonstrate input specific accumulation of A-type potassium channels in thalamic relay cell dendrites. The strong association of large subcortical afferents with postsynapitic Kv4.2/Kv4.3 subunits suggests an effective curtailing of lemniscal sensory EPSPs by A-type K current contrary to paralemniscal and cortical diver EPSPs in VPMvl and Po.
Conference:
12th Meeting of the Hungarian Neuroscience Society, Budapest, Hungary, 22 Jan - 24 Jan, 2009.
Presentation Type:
Poster Presentation
Topic:
Developmental neurobiology and subcortical functions
Citation:
Bokor
H,
Giber
K,
Kollo
M,
Nusser
Z and
Acsady
L
(2009). Input-specific distribution of A-type potassium channels in the thalamus..
Front. Syst. Neurosci.
Conference Abstract:
12th Meeting of the Hungarian Neuroscience Society.
doi: 10.3389/conf.neuro.01.2009.04.048
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Received:
27 Feb 2009;
Published Online:
27 Feb 2009.
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Correspondence:
Hajnalka Bokor, Department of Cellular and Network Neurobiology, Institute of Experimental Medicine, Budapest, Hungary, hbokor@koki.hu