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Event: 669

Key Event Title

A descriptive phrase which defines a discrete biological change that can be measured. More help

Reduction, Neuronal synaptic inhibition

Short name

The KE short name should be a reasonable abbreviation of the KE title and is used in labelling this object throughout the AOP-Wiki. More help

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Key Event Description

A description of the biological state being observed or measured, the biological compartment in which it is measured, and its general role in the biology should be provided. More help

A reduction in GABA-mediated inhibition of neuronal synaptic signaling 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

In the context of the EMOD/M2AOP prototyping, there are 2 components to the How it is Measured or Detected field, a structured component for adding Assay information and a free text component for unstructured descriptive information.In the free text field, include a description of the type(s) of measurements that can be employed to evaluate the KE and the relative level of scientific confidence in those measurements. These can range from citation of specific validated test guidelines, citation of specific methods published in the peer reviewed literature, or outlines of a general protocol or approach (e.g., a protein may be measured by ELISA). Do not provide detailed protocols. More help

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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.

Observations 2.0

Observed meausures are instances of assay results that support this Key Event More help

ID	Experimental Effect	Biological Object	Biological Process	Method of Measurement	Notes	Evidence Source ID	Citation (first author, year)

Observed Measures 1.0

Observed meausures are instances of assay results that support this Key Event More help

ID	Stressor	Sample (short_name)	Assay	Effect

Key Event Components

The KE, as defined by a set structured ontology terms consisting of a biological process, object, and action with each term originating from one of 14 biological ontologies (Ives, et al., 2017; https://aopwiki.org/info_pages/2/info_linked_pages/7#List). Biological process describes dynamics of the underlying biological system (e.g., receptor signalling).Biological process describes dynamics of the underlying biological system (e.g., receptor signaling). The biological object is the subject of the perturbation (e.g., a specific biological receptor that is activated or inhibited). Action represents the direction of perturbation of this system (generally increased or decreased; e.g., ‘decreased’ in the case of a receptor that is inhibited to indicate a decrease in the signaling by that receptor). Note that when editing Event Components, clicking an existing Event Component from the Suggestions menu will autopopulate these fields, along with their source ID and description. To clear any fields before submitting the event component, use the 'Clear process,' 'Clear object,' or 'Clear action' buttons. If a desired term does not exist, a new term request may be made via Term Requests. Event components may not be edited; to edit an event component, remove the existing event component and create a new one using the terms that you wish to add. Further information on Event Components and Biological Context may be viewed on the attached pdf. More help

Process	Object	Action
chemical synaptic transmission		decreased

Biological Context

Structured terms, selected from a drop-down menu, are used to identify the level of biological organization for each KE. More help

Level of Biological Organization
Cellular

Cell term

The location/biological environment in which the event takes place.The biological context describes the location/biological environment in which the event takes place. For molecular/cellular events this would include the cellular context (if known), organ context, and species/life stage/sex for which the event is relevant. For tissue/organ events cellular context is not applicable. For individual/population events, the organ context is not applicable. Further information on Event Components and Biological Context may be viewed on the attached pdf. More help

Cell term
neuron

Organ term

Key Event Overview

AOPs Including This Key Event

All of the AOPs that are linked to this KE will automatically be listed in this subsection. This table can be particularly useful for derivation of AOP networks including the KE.Clicking on the name of the AOP will bring you to the individual page for that AOP. More help

AOP Name	Role of event in AOP	Point of Contact	Author Status	OECD Status
Blocking iGABA receptor ion channel leading to seizures	KeyEvent	Cataia Ives (send email)	Open for citation & comment	WPHA/WNT Endorsed

Taxonomic Applicability

Latin or common names of a species or broader taxonomic grouping (e.g., class, order, family) that help to define the biological applicability domain of the KE.In many cases, individual species identified in these structured fields will be those for which the strongest evidence used in constructing the AOP was available in relation to this KE. More help

Term	Scientific Term	Evidence	Link
rat	Rattus norvegicus	High	NCBI
guinea pig	Cavia porcellus	High	NCBI
human	Homo sapiens	High	NCBI
Japanese quail	Coturnix japonica	High	NCBI

Life Stages

An indication of the the relevant life stage(s) for this KE. More help

Life stage	Evidence
Adult	High

Sex Applicability

An indication of the the relevant sex for this KE. More help

Term	Evidence
Unspecific	High

Evidence Supporting the Domain of Applicability

A description of the scientific basis for the indicated domains of applicability and the WoE calls (if provided). More help

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).

References

List of the literature that was cited for this KE description. More help

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.