Limits...
TTX-resistant NMDA receptor-mediated membrane potential oscillations in neonatal mouse Hb9 interneurons.

Masino MA, Abbinanti MD, Eian J, Harris-Warrick RM - PLoS ONE (2012)

Bottom Line: Hb9 interneurons are rhythmically active during fictive locomotor-like behavior.In contrast, exogenous serotonin and dopamine application, alone or in combination, are not sufficient.NMDA does not modulate the T-type calcium current (I(Ca(T))), which is thought to be important in generating locomotor-like activity, in Hb9 neurons.

View Article: PubMed Central - PubMed

Affiliation: Department of Neuroscience, University of Minnesota, Minneapolis, Minnesota, United States of America. masino@umn.edu

ABSTRACT
Conditional neuronal membrane potential oscillations have been identified as a potential mechanism to help support or generate rhythmogenesis in neural circuits. A genetically identified population of ventromedial interneurons, called Hb9, in the mouse spinal cord has been shown to generate TTX-resistant membrane potential oscillations in the presence of NMDA, serotonin and dopamine, but these oscillatory properties are not well characterized. Hb9 interneurons are rhythmically active during fictive locomotor-like behavior. In this study, we report that exogenous N-Methyl-D-Aspartic acid (NMDA) application is sufficient to produce membrane potential oscillations in Hb9 interneurons. In contrast, exogenous serotonin and dopamine application, alone or in combination, are not sufficient. The properties of NMDA-induced oscillations vary among the Hb9 interneuron population; their frequency and amplitude increase with increasing NMDA concentration. NMDA does not modulate the T-type calcium current (I(Ca(T))), which is thought to be important in generating locomotor-like activity, in Hb9 neurons. These results suggest that NMDA receptor activation is sufficient for the generation of TTX-resistant NMDA-induced membrane potential oscillations in Hb9 interneurons.

Show MeSH

Related in: MedlinePlus

TTX-resistant NMDA-induced membrane potential oscillations in Hb9 interneurons show no voltage dependence. A,Whole-cell current-clamp recordings of membrane potential from a single Hb9 interneuron at various holding potentials. B, Plot of normalized cycle frequency (raw mean at −60 mV  = 0.46±0.06 Hz, range  = 0.4 to 0.5 Hz, n = 7) against holding potential. C, Plot of normalized voltage amplitude (raw mean at −60 mV  = 11.7±14.5 mV, range  = 4.1 to 14.5 mV, n = 7) against holding potential. Data are normalized to −60 mV.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC3475713&req=5

pone-0047940-g004: TTX-resistant NMDA-induced membrane potential oscillations in Hb9 interneurons show no voltage dependence. A,Whole-cell current-clamp recordings of membrane potential from a single Hb9 interneuron at various holding potentials. B, Plot of normalized cycle frequency (raw mean at −60 mV  = 0.46±0.06 Hz, range  = 0.4 to 0.5 Hz, n = 7) against holding potential. C, Plot of normalized voltage amplitude (raw mean at −60 mV  = 11.7±14.5 mV, range  = 4.1 to 14.5 mV, n = 7) against holding potential. Data are normalized to −60 mV.

Mentions: Previous work showed that ‘cocktail’-induced membrane potential oscillations were voltage dependent in a small fraction of Hb9 interneurons [41]. To determine the voltage-dependence of cycle frequency and voltage amplitude of the NMDA-induced oscillations, we varied the trough potential of the membrane potential oscillations above and below the normal resting potential in 7 neurons (5 small amplitude (<15 mV) and 2 large amplitude (>15 mV; Fig. 4A). Neither cycle frequency (F3,19 = 1.09, p = 0.38; Fig. 4B) nor voltage amplitude (F3,18 = 0.63, p = 0.61; Fig. 4C) of the NMDA-induced oscillations was significantly affected by changing the membrane potential across a physiologically relevant range (−50 to −80 mV).


TTX-resistant NMDA receptor-mediated membrane potential oscillations in neonatal mouse Hb9 interneurons.

Masino MA, Abbinanti MD, Eian J, Harris-Warrick RM - PLoS ONE (2012)

TTX-resistant NMDA-induced membrane potential oscillations in Hb9 interneurons show no voltage dependence. A,Whole-cell current-clamp recordings of membrane potential from a single Hb9 interneuron at various holding potentials. B, Plot of normalized cycle frequency (raw mean at −60 mV  = 0.46±0.06 Hz, range  = 0.4 to 0.5 Hz, n = 7) against holding potential. C, Plot of normalized voltage amplitude (raw mean at −60 mV  = 11.7±14.5 mV, range  = 4.1 to 14.5 mV, n = 7) against holding potential. Data are normalized to −60 mV.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3475713&req=5

pone-0047940-g004: TTX-resistant NMDA-induced membrane potential oscillations in Hb9 interneurons show no voltage dependence. A,Whole-cell current-clamp recordings of membrane potential from a single Hb9 interneuron at various holding potentials. B, Plot of normalized cycle frequency (raw mean at −60 mV  = 0.46±0.06 Hz, range  = 0.4 to 0.5 Hz, n = 7) against holding potential. C, Plot of normalized voltage amplitude (raw mean at −60 mV  = 11.7±14.5 mV, range  = 4.1 to 14.5 mV, n = 7) against holding potential. Data are normalized to −60 mV.
Mentions: Previous work showed that ‘cocktail’-induced membrane potential oscillations were voltage dependent in a small fraction of Hb9 interneurons [41]. To determine the voltage-dependence of cycle frequency and voltage amplitude of the NMDA-induced oscillations, we varied the trough potential of the membrane potential oscillations above and below the normal resting potential in 7 neurons (5 small amplitude (<15 mV) and 2 large amplitude (>15 mV; Fig. 4A). Neither cycle frequency (F3,19 = 1.09, p = 0.38; Fig. 4B) nor voltage amplitude (F3,18 = 0.63, p = 0.61; Fig. 4C) of the NMDA-induced oscillations was significantly affected by changing the membrane potential across a physiologically relevant range (−50 to −80 mV).

Bottom Line: Hb9 interneurons are rhythmically active during fictive locomotor-like behavior.In contrast, exogenous serotonin and dopamine application, alone or in combination, are not sufficient.NMDA does not modulate the T-type calcium current (I(Ca(T))), which is thought to be important in generating locomotor-like activity, in Hb9 neurons.

View Article: PubMed Central - PubMed

Affiliation: Department of Neuroscience, University of Minnesota, Minneapolis, Minnesota, United States of America. masino@umn.edu

ABSTRACT
Conditional neuronal membrane potential oscillations have been identified as a potential mechanism to help support or generate rhythmogenesis in neural circuits. A genetically identified population of ventromedial interneurons, called Hb9, in the mouse spinal cord has been shown to generate TTX-resistant membrane potential oscillations in the presence of NMDA, serotonin and dopamine, but these oscillatory properties are not well characterized. Hb9 interneurons are rhythmically active during fictive locomotor-like behavior. In this study, we report that exogenous N-Methyl-D-Aspartic acid (NMDA) application is sufficient to produce membrane potential oscillations in Hb9 interneurons. In contrast, exogenous serotonin and dopamine application, alone or in combination, are not sufficient. The properties of NMDA-induced oscillations vary among the Hb9 interneuron population; their frequency and amplitude increase with increasing NMDA concentration. NMDA does not modulate the T-type calcium current (I(Ca(T))), which is thought to be important in generating locomotor-like activity, in Hb9 neurons. These results suggest that NMDA receptor activation is sufficient for the generation of TTX-resistant NMDA-induced membrane potential oscillations in Hb9 interneurons.

Show MeSH
Related in: MedlinePlus