Glucocorticoids specifically enhance L-type calcium current amplitude and affect calcium channel subunit expression in the mouse hippocampus

Pascal Chameau*, Yongjun Qin, Sabine Spijker, Guus Smit, Marian Joels

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

96 Citations (Scopus)

Abstract

Previous studies have shown that corticosterone enhances whole cell calcium currents in CA1 pyramidal neurons, through a pathway involving binding of glucocorticoid receptor homodimers to the DNA. We examined whether glucocorticoids show selectivity for L- over N-type of calcium currents. Moreover, we addressed the putative gene targets that eventually lead to the enhanced calcium currents. Electrophysiological recordings were performed in nucleated patches that allow excellent voltage control. Calcium currents in these patches almost exclusively involve N- and L-type channels. We found that L-but not N-type calcium currents were largely enhanced after treatment with a high dose of corticosterone sufficient to activate glucocorticoid receptors. Voltage dependency and kinetic properties of the currents were unaffected by the hormone. Nonstationary noise analysis suggests that the increased current is not caused by a larger unitary conductance, but rather to a doubling of the number of functional channels. Quantitative real-time PCR revealed that transcripts of the Ca(v)1 subunits encoding for the N- or L-type calcium channels are not upregulated in the mouse CA1 area; instead, a strong, direct, and consistent upregulation of the beta 4 subunit was observed. This indicates that the corticosteroid-induced increase in number of L-type calcium channels is not caused by a simple transcriptional regulation of the pore-forming subunit of the channels.

Original languageEnglish
Pages (from-to)5-14
Number of pages10
JournalJournal of Neurophysiology
Volume97
Issue number1
DOIs
Publication statusPublished - Jan-2007
Externally publishedYes

Keywords

  • GATED CA2+ CHANNELS
  • RAT HIPPOCAMPUS
  • GENE-EXPRESSION
  • BETA-SUBUNIT
  • SUBCELLULAR-DISTRIBUTION
  • CORTICOSTEROID ACTIONS
  • BRAIN
  • RECEPTOR
  • MODULATION
  • NEURONS

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