Selective regulation of spontaneous activity of neurons of the deep cerebellar nuclei by N-type calcium channels in juvenile rats

Karina Alviña, Kamran Khodakhah

Research output: Contribution to journalArticle

39 Citations (Scopus)

Abstract

The cerebellum coordinates movement and maintains body posture. The main output of the cerebellum is formed by three deep nuclei, which receive direct inhibitory inputs from cerebellar Purkinje cells, and excitatory collaterals from mossy and climbing fibres. Neurons of deep cerebellar nuclei (DCN) are spontaneously active, and disrupting their activity results in severe cerebellar ataxia. It is suggested that voltage-gated calcium channels make a significant contribution to the spontaneous activity of DCN neurons, although the exact identity of these channels is not known. We sought to delineate the functional role and identity of calcium channels that contribute to pacemaking in DCN neurons of juvenile rats. We found that in the majority of cells blockade of calcium currents results in avid high-frequency bursting, consistent with the notion that the net calcium-dependent current in DCN neurons is outward. We showed that the bursting seen in these neurons after block of calcium channels is the consequence of reduced activation of small-conductance calcium-activated (SK) potassium channels. With the use of selective pharmacological blockers we showed that L-, P/Q-, R- and T-type calcium channels do not contribute to the spontaneous activity of DCN neurons. In contrast, blockade of high-threshold N-type calcium channels increased the firing rate and caused the cells to burst. Our results thus suggest a selective coupling of N-type voltage-gated calcium channels with calcium-activated potassium channels in DCN neurons. In addition, we demonstrate the presence of a cadmium-sensitive calcium conductance coupled with SK channels, that is pharmacologically distinct from L-, N-, P/Q-, R- and T-type calcium channels.

Original languageEnglish (US)
Pages (from-to)2523-2538
Number of pages16
JournalJournal of Physiology
Volume586
Issue number10
DOIs
StatePublished - May 15 2008

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N-Type Calcium Channels
Cerebellar Nuclei
Neurons
Calcium Channels
R-Type Calcium Channels
Small-Conductance Calcium-Activated Potassium Channels
T-Type Calcium Channels
Calcium
Cerebellum
Calcium-Activated Potassium Channels
Cerebellar Ataxia
Purkinje Cells
Posture
Cadmium
Pharmacology

ASJC Scopus subject areas

  • Physiology

Cite this

Selective regulation of spontaneous activity of neurons of the deep cerebellar nuclei by N-type calcium channels in juvenile rats. / Alviña, Karina; Khodakhah, Kamran.

In: Journal of Physiology, Vol. 586, No. 10, 15.05.2008, p. 2523-2538.

Research output: Contribution to journalArticle

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