Riluzole-induced oscillations in spinal networks

Yvon, Cédric; Czarnecki, Antonny; Streit, Jürg (2007). Riluzole-induced oscillations in spinal networks. Journal of neurophysiology, 97(5), pp. 3607-20. Bethesda, Md.: American Physiological Society 10.1152/jn.00924.2006

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We previously showed in dissociated cultures of fetal rat spinal cord that disinhibition-induced bursting is based on intrinsic spiking, network recruitment, and a network refractory period after the bursts. A persistent sodium current (I(NaP)) underlies intrinsic spiking, which, by recurrent excitation, generates the bursting activity. Although full blockade of I(NaP) with riluzole disrupts such bursting, the present study shows that partial blockade of I(NaP) with low doses of riluzole maintains bursting activity with unchanged burst rate and burst duration. More important, low doses of riluzole turned bursts composed of persistent activity into bursts composed of oscillatory activity at around 5 Hz. In a search for the mechanisms underlying the generation of such intraburst oscillations, we found that activity-dependent synaptic depression was not changed with low doses of riluzole. On the other hand, low doses of riluzole strongly increased spike-frequency adaptation and led to early depolarization block when bursts were simulated by injecting long current pulses into single neurons in the absence of fast synaptic transmission. Phenytoin is another I(NaP) blocker. When applied in doses that reduced intrinsic activity by 80-90%, as did low doses of riluzole, it had no effect either on spike-frequency adaptation or on depolarization block. Nor did phenytoin induce intraburst oscillations after disinhibition. A theoretical model incorporating a depolarization block mechanism could reproduce the generation of intraburst oscillations at the network level. From these findings we conclude that riluzole-induced intraburst oscillations are a network-driven phenomenon whose major accommodation mechanism is depolarization block arising from strong sodium channel inactivation.

Item Type:

Journal Article (Original Article)

Division/Institute:

04 Faculty of Medicine > Pre-clinic Human Medicine > Institute of Physiology

UniBE Contributor:

Streit, Jürg

ISSN:

0022-3077

ISBN:

17344372

Publisher:

American Physiological Society

Language:

English

Submitter:

Factscience Import

Date Deposited:

04 Oct 2013 14:53

Last Modified:

04 May 2014 23:15

Publisher DOI:

10.1152/jn.00924.2006

PubMed ID:

17344372

Web of Science ID:

000247933500042

URI:

https://boris.unibe.ch/id/eprint/22301 (FactScience: 33926)

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