Institut de Neurosciences Cognitives et Intégratives d'Aquitaine (UMR5287)

Aquitaine Institute for Cognitive and Integrative Neuroscience



INCIA - UMR 5287- CNRS
Université de Bordeaux

Zone nord Bat 2 2ème étage
146, rue Léo Saignat
33076 Bordeaux cedex
France

Téléphone 05.57.57.15.51
Télécopie 05.56.90.14.21

Supervisory authorities

CNRS Ecole Pratique des Hautes Etudes Université de Bordeaux

Our partners

Neurocampus Unitéde Formation de Biologie

GDR

GDR Robotique GDR Mémoire GDR Multi-électrodes

Search




Home > Latest publications

Juliette Boeri, Hervé Le Corronc, François-Xavier Lejeune, Barbara Le Bras, Christine Mouffle, Monara Kaelle S.C. Angelim, Jean-Marie Mangin, Pascal Branchereau, Pascal Legendre and Antonny Czarnecki. Journal of Neuroscience 2018, 38 (35) 7667-7682

by Wolff - published on , updated on

Persistent Sodium Current Drives Excitability of Persistent Sodium Current Drives Excitability of Immature Renshaw Cells in Early Embryonic Spinal Networks.
Juliette Boeri, Hervé Le Corronc, François-Xavier Lejeune, Barbara Le Bras, Christine Mouffle, Monara Kaelle S.C. Angelim, Jean-Marie Mangin, Pascal Branchereau, Pascal Legendre and Antonny Czarnecki
ournal of Neuroscience 29 August 2018, 38 (35) 7667-7682; DOI: https://doi.org/10.1523/JNEUROSCI.3203-17.2018

Abstract
Spontaneous network activity (SNA) emerges in the spinal cord (SC) before the formation of peripheral sensory inputs and central descending inputs. SNA is characterized by recurrent giant depolarizing potentials (GDPs). Because GDPs in motoneurons (MNs) are mainly evoked by prolonged release of GABA, they likely necessitate sustained firing of interneurons. To address this issue we analyzed, as a model, embryonic Renshaw cell (V1R) activity at the onset of SNA (E12.5) in the embryonic mouse SC (both sexes). V1R are one of the interneurons known to contact MNs, which are generated early in the embryonic SC. Here, we show that V1R already produce GABA in E12.5 embryo, and that V1R make synaptic-like contacts with MNs and have putative extrasynaptic release sites, while paracrine release of GABA occurs at this developmental stage. In addition, we discovered that V1R are spontaneously active during SNA and can already generate several intrinsic activity patterns including repetitive-spiking and sodium-dependent plateau potential that rely on the presence of persistent sodium currents (INap). This is the first demonstration that INap is present in the embryonic SC and that this current can control intrinsic activation properties of newborn interneurons in the SC of mammalian embryos. Finally, we found that 5 μm riluzole, which is known to block INaP, altered SNA by reducing episode duration and increasing inter-episode interval. Because SNA is essential for neuronal maturation, axon pathfinding, and synaptogenesis, the presence of INaP in embryonic SC neurons may play a role in the early development of mammalian locomotor networks.

SIGNIFICANCE STATEMENT The developing spinal cord (SC) exhibits spontaneous network activity (SNA) involved in the building of nascent locomotor circuits in the embryo. Many studies suggest that SNA depends on the rhythmic release of GABA, yet intracellular recordings of GABAergic neurons have never been performed at the onset of SNA in the SC. We first discovered that embryonic Renshaw cells (V1R) are GABAergic at E12.5 and spontaneously active during SNA. We uncover a new role for persistent sodium currents (INaP) in driving plateau potential in V1R and in SNA patterning in the embryonic SC. Our study thus sheds light on a role for INaP in the excitability of V1R and the developing SC.