From AOP-Wiki
Jump to: navigation, search

Event Title

Neuronal synaptic inhibition, Reduction

Key Event Overview

Please follow link to widget page to edit this section.

If you manually enter text in this section, it will get automatically altered or deleted in subsequent edits using the widgets.

AOPs Including This Key Event

AOP Name Event Type Essentiality
Binding to the picrotoxin site of ionotropic GABA receptors leading to epileptic seizures KE Strong

Taxonomic Applicability

Name Scientific Name Evidence Links
rat Rattus norvegicus Strong NCBI
guinea pig Cavia porcellus Strong NCBI
human Homo sapiens Strong NCBI
Japanese quail Coturnix japonica Strong NCBI

Level of Biological Organization

Biological Organization

How this Key Event works

A decline in conductance through chloride channels in iGABARs causes a reduction in GABA-mediated inhibition of neuronal synaptic signalling, which is reflected as decreased frequency and amplitude of iGABAR-mediated spontaneous inhibitory postsynaptic currents (sIPSCs) or abolishment of GABA-induced firing action (Newland and Cull-Candy 1992).

How it is Measured or Detected

Juarez et al. (2013) used primary cultured neurons obtained from the guinea-pig small intestine to detect picrotoxin concentration-dependent (and reversible) inhibition of GABA-induced membrane currents. Williams et al. (2011) used whole-cell in vitro recordings in the rat basolateral amygdala (BLA) to detect the reduced frequency and amplitude of GABA-A receptor mediated spontaneous inhibitory postsynaptic currents (sIPSCs) and the amplitude of GABA-evoked postsynaptic currents, both of which were induced by RDX.

Evidence Supporting Taxonomic Applicability

See Juarez et al. (2013) for supporting evidence for Guinea pig; For rat, whole-cell in vitro recordings in the rat basolateral amygdala (BLA) showed that RDX reduces the frequency and amplitude of GABA-A receptor mediated sIPSCs and the amplitude of GABA-evoked postsynaptic currents, whereas in extracellular field recordings from the BLA, RDX induced prolonged, seizure-like neuronal discharges (Williams et al, 2011).


Newland C F, Cull-Candy S G. On the mechanism of action of picrotoxin on GABA receptor channels in dissociated sympathetic neurones of the rat. J Physiol 1992; 447: 191–213.

Juarez E H, Ochoa-Cortes F, Miranda-Morales M, Espinosa-Luna R, Montano L M, Barajas-Lopez C. Selectivity of antagonists for the Cys-loop native receptors for ACh, 5-HT and GABA in guinea-pig myenteric neurons. Auton Autacoid Pharmacol 2013; 34(1-2):1-8.

Williams L R, Aroniadou-Anderjaska V, Qashu F, Finne H, Pidoplichko V, Bannon D I et al. RDX binds to the GABA(A) receptor-convulsant site and blocks GABA(A) receptor-mediated currents in the amygdala: a mechanism for RDX-induced seizures. Environ Health Perspect 2011; 119(3):357-363.