Format

Send to

Choose Destination
Mol Neurobiol. 2018 Nov;55(11):8509-8521. doi: 10.1007/s12035-018-0984-1. Epub 2018 Mar 20.

Presynaptic Regulation of Tonic Inhibition by Neuromodulatory Transmitters in the Basal Amygdala.

Author information

1
Institut für Physiologie, Otto-von-Guericke-Universität, Leipziger Str. 44, D-39120, Magdeburg, Germany. susanne.meis@med.ovgu.de.
2
Center for Behavioral Brain Sciences, Magdeburg, Germany. susanne.meis@med.ovgu.de.
3
Institut für Physiologie, Otto-von-Guericke-Universität, Leipziger Str. 44, D-39120, Magdeburg, Germany.
4
Center for Behavioral Brain Sciences, Magdeburg, Germany.
5
Institut für Physiologie, Otto-von-Guericke-Universität, Leipziger Str. 44, D-39120, Magdeburg, Germany. lessmann@med.ovgu.de.
6
Center for Behavioral Brain Sciences, Magdeburg, Germany. lessmann@med.ovgu.de.

Abstract

Tonic inhibition mediated by ambient levels of GABA that activate extrasynaptic GABAA receptors emerges as an essential factor that tunes neuronal network excitability in vitro and shapes behavioral responses in vivo. To address the role of neuromodulatory transmitter systems on this type of inhibition, we employed patch clamp recordings in mouse amygdala slice preparations. Our results show that the current amplitude of tonic inhibition (Itonic) in projection neurons of the basal amygdala (BA) is increased by preincubation with the neurosteroid THDOC, while the benzodiazepine diazepam is ineffective. This suggests involvement of THDOC sensitive δ subunit containing GABAA receptors in mediating tonic inhibition. Moreover, we provide evidence that the neuromodulatory transmitters NE, 5HT, and ACh strongly enhance spontaneous IPSCs as well as Itonic in the BA. As the increase in frequency, amplitude, and charge of sIPSCs by these neuromodulatory transmitters strongly correlated with the amplitude of Itonic, we conclude that spill-over of synaptic GABA leads to activation of Itonic and thereby to dampening of amygdala excitability. Since local injection of THDOC, as a positive modulator of tonic inhibition, into the BA interfered with the expression of contextual fear memory, our results point to a prominent role of Itonic in fear learning.

KEYWORDS:

5HT; Amygdala; GABA; Nicotine; Norepinephrine; Tonic inhibition

PMID:
29560580
DOI:
10.1007/s12035-018-0984-1
[Indexed for MEDLINE]

Supplemental Content

Full text links

Icon for Springer
Loading ...
Support Center