Immunocytochemical localization of small-conductance, calcium-dependent potassium channels in astrocytes of the rat supraoptic nucleus

William E. Armstrong, Adam Rubrum, Ryoichi Teruyama, Chris T. Bond, John Adelman

Research output: Contribution to journalArticle

33 Citations (Scopus)

Abstract

Supraoptic nucleus (SON) neurons possess a prominent afterhyperpolarization (AHP) that contributes to spike patterning. This AHP is probably underlain by a small-conductance, CA2+-dependent, K+ type 3 (SK3) channel. To determine the distribution of SK3 channels within the SON, we used immunocytochemistry in rats and in transgenic mice with a regulatory cassette on the SK3 gene, allowing regulated expression with dietary doxycycline (DOX). In rats and wild-type mice, SK3 immunostaining revealed an intense lacy network surrounding SON neurons, with weak staining in neuronal somata and dendrites. In untreated, conditional SK3 knockout mice, SK3 was overexpressed, but the pericellular pattern in the SON was similar to that of rats. DOX-treated transgenic mice exhibited no SK3 staining in the SON. Double staining for oxytocin or vasopressin neurons revealed weak co-localization with SK3 but strong staining surrounding each neuron type. Electron microscopy showed that SK3-like immunoreactivity was intense between neuronal somata and dendrites, in apparent glial processes, but weak in neurons. This was confirmed by using confocal microscopy and double staining for glial fibrillary acidic protein (GFAP) and SK3: many GFAP-positive processes in the SON, and in the ventral dendritic/glial lamina, were shown to contain SK3-like immunoreactivity. These studies suggest a prominent role of SK3 channels in astrocytes. Given the marked plasticity in glial/neuronal relationships, as well as studies suggesting that astrocytes in the central nervous system can generate prominent CA2+ transients to various stimuli, a CA2+-dependent K+ channel may help SON astrocytes with K+ buffering whenever astrocyte intracellular CA2+ is increased.

Original languageEnglish (US)
Pages (from-to)175-185
Number of pages11
JournalJournal of Comparative Neurology
Volume491
Issue number3
DOIs
StatePublished - Oct 24 2005

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Calcium-Activated Potassium Channels
Supraoptic Nucleus
Astrocytes
Staining and Labeling
Neurons
Neuroglia
Doxycycline
Glial Fibrillary Acidic Protein
Carisoprodol
Dendrites
Transgenic Mice
Oxytocin
Vasopressins
Knockout Mice
Confocal Microscopy
Electron Microscopy
Central Nervous System
Immunohistochemistry
Genes

Keywords

  • Afterhyperpolarization
  • Glial fibrillary acidic protein
  • Oxytocin
  • SK3
  • Vasopressin

ASJC Scopus subject areas

  • Neuroscience(all)

Cite this

Immunocytochemical localization of small-conductance, calcium-dependent potassium channels in astrocytes of the rat supraoptic nucleus. / Armstrong, William E.; Rubrum, Adam; Teruyama, Ryoichi; Bond, Chris T.; Adelman, John.

In: Journal of Comparative Neurology, Vol. 491, No. 3, 24.10.2005, p. 175-185.

Research output: Contribution to journalArticle

Armstrong, William E. ; Rubrum, Adam ; Teruyama, Ryoichi ; Bond, Chris T. ; Adelman, John. / Immunocytochemical localization of small-conductance, calcium-dependent potassium channels in astrocytes of the rat supraoptic nucleus. In: Journal of Comparative Neurology. 2005 ; Vol. 491, No. 3. pp. 175-185.
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