TY - JOUR
T1 - Low-threshold calcium currents contribute to locomotor-like activity in neonatal mice
AU - Anderson, Tatiana M.
AU - Abbinanti, Matthew D.
AU - Peck, Jack H.
AU - Gilmour, Megan
AU - Brownstone, Robert M.
AU - Masino, Mark A.
PY - 2012/1
Y1 - 2012/1
N2 - 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.
AB - 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.
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U2 - 10.1152/jn.00583.2011
DO - 10.1152/jn.00583.2011
M3 - Article
C2 - 21994264
AN - SCOPUS:84255182645
SN - 1522-1598
VL - 107
SP - 103
EP - 113
JO - Journal of Neurophysiology
JF - Journal of Neurophysiology
IS - 1
ER -