Low-threshold calcium currents contribute to locomotor-like activity in neonatal mice

Tatiana M. Anderson, Matthew D. Abbinanti, Jack H. Peck, Megan Gilmour, Robert M. Brownstone, Mark A. Masino

Research output: Contribution to journalArticlepeer-review

10 Scopus citations

Abstract

In this study, we examined the contribution of a low-threshold calcium current [I Ca(T)] to locomotor-related activity in the neonatal mouse. Specifically, the role of I Ca(T) was studied during chemically induced, locomotor-like activity in the isolated whole cord and in a genetically distinct population of ventromedial spinal interneu-rons marked by the homeobox gene Hb9. In isolated whole spinal cords, cycle frequency was decreased in the presence of low-threshold calcium channel blockers, which suggests a role for I Ca(T) in the network that produces rhythmic, locomotor-like activity. Additionally, we used Hb9 interneurons as a model to study the cellular responses to application of low-threshold calcium channel blockers. In transverse slice preparations from transgenic Hb9::enhanced green fluorescent protein neonatal mice, N-methyl-D-aspartate-induced membrane potential oscillations in identified Hb9 interneurons also slowed in frequency with application of nickel when fast, spike-mediated, synaptic transmission was blocked with TTX. Voltage-clamp and immunolabeling experiments confirmed expression of I Ca(T) and channels, respectively, in Hb9 interneurons located in the ventromedial spinal cord. Taken together, these results provide support that T-type calcium currents play an important role in network-wide rhythm generation during chemically evoked, fictive locomotor activity.

Original languageEnglish (US)
Pages (from-to)103-113
Number of pages11
JournalJournal of Neurophysiology
Volume107
Issue number1
DOIs
StatePublished - Jan 2012

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