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AOP: 169

Title

A descriptive phrase which references both the Molecular Initiating Event and Adverse Outcome.It should take the form “MIE leading to AO”. For example, “Aromatase inhibition leading to reproductive dysfunction” where Aromatase inhibition is the MIE and reproductive dysfunction the AO. In cases where the MIE is unknown or undefined, the earliest known KE in the chain (i.e., furthest upstream) should be used in lieu of the MIE and it should be made clear that the stated event is a KE and not the MIE. More help

GnRH pulse disruption leading to pituitary adenomas and carcinomas in the SD rat.

Short name

A name that succinctly summarises the information from the title. This name should not exceed 90 characters. More help

GnRH pulse disruption and pituitary tumors

Graphical Representation

A graphical representation of the AOP.This graphic should list all KEs in sequence, including the MIE (if known) and AO, and the pair-wise relationships (links or KERs) between those KEs. More help

Click to download graphical representation template Explore AOP in a Third Party Tool

Authors

The names and affiliations of the individual(s)/organisation(s) that created/developed the AOP. More help

Cancer AOP Workgroup. National Health and Environmental Effects Research Laboratory, Office of Research and Development, Integrated Systems Toxicology Division, US Environmental Protection Agency, Research Triangle Park, NC. Corresponding author for wiki entry (wood.charles@epa.gov)

Point of Contact

The user responsible for managing the AOP entry in the AOP-KB and controlling write access to the page by defining the contributors as described in the next section. More help

Charles Wood (email point of contact)

Contributors

Users with write access to the AOP page. Entries in this field are controlled by the Point of Contact. More help

Charles Wood

Coaches

This field is used to identify coaches who supported the development of the AOP.Each coach selected must be a registered author. More help

Status

Provides users with information concerning how actively the AOP page is being developed, what type of use or input the authors feel comfortable with given the current level of development, and whether it is part of the OECD AOP Development Workplan and has been reviewed and/or endorsed. OECD Status - Tracks the level of review/endorsement the AOP has been subjected to. OECD Project Number - Project number is designated and updated by the OECD. SAAOP Status - Status managed and updated by SAAOP curators. More help

Handbook Version	OECD status	OECD project
v1.0		1.29

This AOP was last modified on April 29, 2023 16:02

Revision dates for related pages

Page	Revision Date/Time
Decreased, GnRH pulsatility/release in hypothalamus	September 16, 2017 10:17
Decreased, LH Surge from anterior pituitary	December 03, 2016 16:37
prolonged, estrus	December 03, 2016 16:37
interruption, Ovulation	December 03, 2016 16:37
Increased, circulating estrogen levels	December 03, 2016 16:37
Increased, lactotroph hyperplasia and hypertrophy	September 16, 2017 10:17
Increased, adenomas (pituitary)	September 16, 2017 10:17
Decreased, GnRH pulsatility/release in hypothalamus leads to Decreased, LH Surge from anterior pituitary	December 03, 2016 16:38
Decreased, LH Surge from anterior pituitary leads to prolonged, estrus	December 03, 2016 16:38
Decreased, LH Surge from anterior pituitary leads to interruption, Ovulation	December 03, 2016 16:38
prolonged, estrus leads to Increased, circulating estrogen levels	December 03, 2016 16:38
interruption, Ovulation leads to Increased, circulating estrogen levels	December 03, 2016 16:38
Increased, circulating estrogen levels leads to Increased, lactotroph hyperplasia and hypertrophy	December 03, 2016 16:38
Increased, lactotroph hyperplasia and hypertrophy leads to Increased, adenomas (pituitary)	December 03, 2016 16:38
atrazine	November 29, 2016 18:42

Abstract

A concise and informative summation of the AOP under development that can stand-alone from the AOP page. The aim is to capture the highlights of the AOP and its potential scientific and regulatory relevance. More help

This putative adverse outcome pathway (AOP) outlines potential key events leading to a tumor outcome in standard carcinogenicity models. This information is based largely on modes of action described previously in cited literature sources and is intended as a resource template for AOP development and data organization. Presentation in this Wiki does not indicate EPA acceptance of a particular pathway for a given reference agent, only that the information has been proposed in some manner. In addition, this putative AOP relates to the model species indicated and does not directly address issues of human relevance.

AOP Development Strategy

Context

Used to provide background information for AOP reviewers and users that is considered helpful in understanding the biology underlying the AOP and the motivation for its development.The background should NOT provide an overview of the AOP, its KEs or KERs, which are captured in more detail below. More help

Strategy

Provides a description of the approaches to the identification, screening and quality assessment of the data relevant to identification of the key events and key event relationships included in the AOP or AOP network.This information is important as a basis to support the objective/envisaged application of the AOP by the regulatory community and to facilitate the reuse of its components. Suggested content includes a rationale for and description of the scope and focus of the data search and identification strategy/ies including the nature of preliminary scoping and/or expert input, the overall literature screening strategy and more focused literature surveys to identify additional information (including e.g., key search terms, databases and time period searched, any tools used). More help

Summary of the AOP

This section is for information that describes the overall AOP.The information described in section 1 is entered on the upper portion of an AOP page within the AOP-Wiki. This is where some background information may be provided, the structure of the AOP is described, and the KEs and KERs are listed. More help

Events:

Molecular Initiating Events (MIE)

An MIE is a specialised KE that represents the beginning (point of interaction between a prototypical stressor and the biological system) of an AOP. More help

Key Events (KE)

A measurable event within a specific biological level of organisation. More help

Adverse Outcomes (AO)

An AO is a specialized KE that represents the end (an adverse outcome of regulatory significance) of an AOP. More help

Type	Event ID	Title	Short name

KE	1071	Decreased, GnRH pulsatility/release in hypothalamus	Decreased, GnRH pulsatility/release in hypothalamus
KE	1072	Decreased, LH Surge from anterior pituitary	Decreased, LH Surge from anterior pituitary
KE	1075	prolonged, estrus	prolonged, estrus
KE	1074	interruption, Ovulation	interruption, Ovulation
KE	1076	Increased, circulating estrogen levels	Increased, circulating estrogen levels
KE	1081	Increased, lactotroph hyperplasia and hypertrophy	Increased, lactotroph hyperplasia and hypertrophy

1082

Increased, adenomas (pituitary)

Relationships Between Two Key Events (Including MIEs and AOs)

This table summarizes all of the KERs of the AOP and is populated in the AOP-Wiki as KERs are added to the AOP.Each table entry acts as a link to the individual KER description page. More help

Title	Adjacency	Evidence	Quantitative Understanding

Decreased, GnRH pulsatility/release in hypothalamus leads to Decreased, LH Surge from anterior pituitary	adjacent	High
Decreased, LH Surge from anterior pituitary leads to interruption, Ovulation	adjacent	High
prolonged, estrus leads to Increased, circulating estrogen levels	adjacent	High
Increased, circulating estrogen levels leads to Increased, lactotroph hyperplasia and hypertrophy	adjacent	High

Decreased, LH Surge from anterior pituitary leads to prolonged, estrus	non-adjacent	High
interruption, Ovulation leads to Increased, circulating estrogen levels	non-adjacent	High
Increased, lactotroph hyperplasia and hypertrophy leads to Increased, adenomas (pituitary)	non-adjacent	High

Network View

This network graphic is automatically generated based on the information provided in the MIE(s), KEs, AO(s), KERs and Weight of Evidence (WoE) summary tables. The width of the edges representing the KERs is determined by its WoE confidence level, with thicker lines representing higher degrees of confidence. This network view also shows which KEs are shared with other AOPs. More help

Prototypical Stressors

A structured data field that can be used to identify one or more “prototypical” stressors that act through this AOP. Prototypical stressors are stressors for which responses at multiple key events have been well documented. More help

Name
atrazine

Life Stage Applicability

The life stage for which the AOP is known to be applicable. More help

Taxonomic Applicability

Latin or common names of a species or broader taxonomic grouping (e.g., class, order, family) can be selected.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. More help

Term	Scientific Term	Evidence	Link
SD rat	Rattus norvegicus	High	NCBI

Sex Applicability

The sex for which the AOP is known to be applicable. More help

Sex	Evidence
Female	High

Overall Assessment of the AOP

Addressess the relevant biological domain of applicability (i.e., in terms of taxa, sex, life stage, etc.) and Weight of Evidence (WoE) for the overall AOP as a basis to consider appropriate regulatory application (e.g., priority setting, testing strategies or risk assessment). More help

Domain of Applicability

Addressess the relevant biological domain(s) of applicability in terms of sex, life-stage, taxa, and other aspects of biological context. More help

Essentiality of the Key Events

The essentiality of KEs can only be assessed relative to the impact of manipulation of a given KE (e.g., experimentally blocking or exacerbating the event) on the downstream sequence of KEs defined for the AOP. Consequently, evidence supporting essentiality is assembled on the AOP page, rather than on the independent KE pages that are meant to stand-alone as modular units without reference to other KEs in the sequence. The nature of experimental evidence that is relevant to assessing essentiality relates to the impact on downstream KEs and the AO if upstream KEs are prevented or modified. This includes: Direct evidence: directly measured experimental support that blocking or preventing a KE prevents or impacts downstream KEs in the pathway in the expected fashion. Indirect evidence: evidence that modulation or attenuation in the magnitude of impact on a specific KE (increased effect or decreased effect) is associated with corresponding changes (increases or decreases) in the magnitude or frequency of one or more downstream KEs. More help

Evidence Assessment

Addressess the biological plausibility, empirical support, and quantitative understanding from each KER in an AOP. More help

Known Modulating Factors

Modulating factors (MFs) may alter the shape of the response-response function that describes the quantitative relationship between two KES, thus having an impact on the progression of the pathway or the severity of the AO.The evidence supporting the influence of various modulating factors is assembled within the individual KERs. More help

Quantitative Understanding

Optional field to provide quantitative weight of evidence descriptors. More help

Considerations for Potential Applications of the AOP (optional)

Addressess potential applications of an AOP to support regulatory decision-making.This may include, for example, possible utility for test guideline development or refinement, development of integrated testing and assessment approaches, development of (Q)SARs / or chemical profilers to facilitate the grouping of chemicals for subsequent read-across, screening level hazard assessments or even risk assessment. More help

References

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

1. O'Connor, J. C., Davis, L. G., Frame, S. R., and Cook, J. C. (2000). Detection of dopaminergic modulators in a tier I screening battery for identifying endocrine-active compounds (EACs). Reproductive toxicology 14(3), 193-205.