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TitleCalcium influx through N-type channels and activation of SK and TRP-like channels regulates tonic firing of neurons in rat paraventricular thalamus.
Publication TypeJournal Article
Year of Publication2013
AuthorsWong, Adrian Y. C., Jean-Francois Borduas, Stephen Clarke, Kevin F. H. Lee, Jean-Claude Béïque, and Richard Bergeron
JournalJ Neurophysiol
Volume110
Issue10
Pagination2450-64
Date Published2013 Nov
ISSN1522-1598
KeywordsAction Potentials, Animals, Calcium, Calcium Channels, N-Type, Midline Thalamic Nuclei, Neurons, Rats, Rats, Sprague-Dawley, Small-Conductance Calcium-Activated Potassium Channels, Transient Receptor Potential Channels
Abstract

The thalamus is a major relay and integration station in the central nervous system. While there is a large body of information on the firing and network properties of neurons contained within sensory thalamic nuclei, less is known about the neurons located in midline thalamic nuclei, which are thought to modulate arousal and homeostasis. One midline nucleus that has been implicated in mediating stress responses is the paraventricular nucleus of the thalamus (PVT). Like other thalamic neurons, these neurons display two distinct firing modes, burst and tonic. In contrast to burst firing, little is known about the ionic mechanisms modulating tonic firing in these cells. Here we performed a series of whole cell recordings to characterize tonic firing in PVT neurons in acute rat brain slices. We found that PVT neurons are able to fire sustained, low-frequency, weakly accommodating trains of action potentials in response to a depolarizing stimulus. Unexpectedly, PVT neurons displayed a very high propensity to enter depolarization block, occurring at stimulus intensities that would elicit tonic firing in other thalamic neurons. The tonic firing behavior of these cells is modulated by a functional interplay between N-type Ca(2+) channels and downstream activation of small-conductance Ca(2+)-dependent K(+) (SK) channels and a transient receptor potential (TRP)-like conductance. Thus these ionic conductances endow PVT neurons with a narrow dynamic range, which may have fundamental implications for the integrative properties of this nucleus.

DOI10.1152/jn.00363.2013
Alternate JournalJ. Neurophysiol.
PubMed ID24004531
Grant ListMOP-115061 / / Canadian Institutes of Health Research / Canada
MOP-79360 / / Canadian Institutes of Health Research / Canada