Depolarizing GABA/glycine synaptic events switch from excitation to inhibition during frequency increases
Sci Rep. 2016-02-25; 6(1):
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1. Sci Rep. 2016 Feb 25;6:21753. doi: 10.1038/srep21753.
Depolarizing GABA/glycine synaptic events switch from excitation to inhibition
during frequency increases.
Branchereau P(1)(2), Cattaert D(1)(2), Delpy A(1)(2), Allain AE(1)(2), Martin
E(1)(2), Meyrand P(1)(2).
(1)Univ. Bordeaux, INCIA, UMR 5287, F-33615 Pessac, France.
(2)CNRS, INCIA, UMR 5287, F-33615 Pessac, France.
By acting on their ionotropic chloride channel receptors, GABA and glycine
represent the major inhibitory transmitters of the central nervous system.
Nevertheless, in various brain structures, depolarizing GABAergic/glycinergic
postsynaptic potentials (dGPSPs) lead to dual inhibitory (shunting) and
excitatory components, the functional consequences of which remain poorly
acknowledged. Indeed, the extent to which each component prevails during dGPSP is
unclear. Understanding the mechanisms predicting the dGPSP outcome on neural
network activity is therefore a major issue in neurobiology. By combining
electrophysiological recordings of spinal embryonic mouse motoneurons and
modelling study, we demonstrate that increasing the chloride conductance (g(Cl))
favors inhibition either during a single dGPSP or during trains in which g(Cl)
summates. Finally, based on this summation mechanism, the excitatory effect of
EPSPs is overcome by dGPSPs in a frequency-dependent manner. These results reveal
an important mechanism by which dGPSPs protect against the overexcitation of
neural excitatory circuits.
PMID: 26912194 [Indexed for MEDLINE]