title: Low-threshold calcium currents contribute to locomotor-like activity in neonatal mice.
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 interneurons 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.
authors: Dept. of Neuroscience, Univ. of Minnesota, 321 Church St., Minneapolis, MN 55455, USA.
authors: Tatiana M
authors: TM
authors: Anderson
authors: Matthew D
authors: MD
authors: Abbinanti
authors: Jack H
authors: JH
authors: Peck
authors: Megan
authors: M
authors: Gilmour
authors: Robert M
authors: RM
authors: Brownstone
authors: Mark A
authors: MA
authors: Masino
mesh_terms: D000200:Action Potentials / Q000502:physiology*; D000818:Animals; D000831:Animals, Newborn; D001683:Biological Clocks / Q000502:physiology*; D002118:Calcium / Q000378:metabolism*; D020747:Calcium Channels, T-Type / Q000502:physiology*; D020013:Calcium Signaling / Q000502:physiology; D002460:Cell Line; D004056:Differential Threshold / Q000502:physiology; D007395:Interneurons / Q000502:physiology*; D008124:Locomotion / Q000502:physiology*; D051379:Mice; D008822:Mice, Transgenic; D009415:Nerve Net / Q000502:physiology; D013116:Spinal Cord / Q000502:physiology*
chemical_list: D020747:Calcium Channels, T-Type; D002118:Calcium