OECD Series on Adverse Outcome Pathways
An Adverse Outcome Pathway (AOP) describes a logical sequence of causally linked events at different levels of biological organisation, which follows exposure to a stressor and leads to an adverse health effect in humans or wildlife. AOPs are the central element of a toxicological knowledge framework, promoted by member countries through OECD, built to support chemical risk assessment based on mechanistic reasoning. These AOPs are available in the AOP-Wiki, an interactive and virtual encyclopaedia for AOP development. Following their development and review, the endorsed AOPs are published in the OECD Series on Adverse Outcome Pathways. As scientific knowledge progresses, the publication of an AOP in this series does not preclude regular updates or new contributions to a given AOP. While the AOP-Wiki is a dynamic tool, only impactful changes to the AOP will be reflected in subsequent updates of the published AOP.
- ISSN: 2415170X (online)
- https://doi.org/10.1787/2415170X
Deiodinase 1 inhibition leading to increased mortality via reduced posterior swim bladder inflation
This Adverse Outcome Pathway (AOP) describes the linkage between Deiodinase 1 inhibition and increased mortality via reduced posterior swim bladder inflation. The swim bladder is a gas-filled organ found in many bony fish species and typically consists of two gas-filled chambers. The posterior chamber inflates during early development (embryo), while the anterior chamber inflates during late development (larva). Both chambers are important for fish to control buoyancy and the anterior chamber has an additional role in hearing. This AOP is part of a network of 5 AOPs describing how disruption of the thyroid hormone system can affect developmental processes involved in swim bladder inflation. The network includes three molecular initiating events representing the inhibition of enzymes that are important for thyroid hormone synthesis and activation. It describes how inhibition of thyroperoxidase and/or deiodinase, leads to reduced swim bladder inflation, resulting in reduced swimming performance, increased mortality and ultimately, decreased population trajectory in fish. This AOP network is currently mainly based on experimental evidence from studies on fish species with a two-chambered swim bladder. This AOP is referred to as AOP 157 in the Collaborative Adverse Outcome Pathway Wiki (AOP-Wiki).
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