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Event: 1756

Key Event Title

The KE title should describe a discrete biological change that can be measured. It should generally define the biological object or process being measured and whether it is increased, decreased, or otherwise definably altered relative to a control state. For example “enzyme activity, decreased”, “hormone concentration, increased”, or “growth rate, decreased”, where the specific enzyme or hormone being measured is defined. More help

Decreased, plasma 11-ketotestosterone level

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. The short name should be less than 80 characters in length. More help
Decreased, 11KT

Biological Context

Structured terms, selected from a drop-down menu, are used to identify the level of biological organization for each KE. Note, KEs should be defined within a particular level of biological organization. Only KERs should be used to transition from one level of organization to another. Selection of the level of biological organization defines which structured terms will be available to select when defining the Event Components (below). More help

Organ term

Further information on Event Components and Biological Context may be viewed on the attached pdf.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. More help
Organ term
blood plasma

Key Event Components

Further information on Event Components and Biological Context may be viewed on the attached pdf.Because one of the aims of the AOP-KB is to facilitate de facto construction of AOP networks through the use of shared KE and KER elements, authors are also asked to define their KEs using a set of structured ontology terms (Event Components). In the absence of structured terms, the same KE can readily be defined using a number of synonymous titles (read by a computer as character strings). In order to make these synonymous KEs more machine-readable, KEs should also be defined by one or more “event components” consisting of a biological process, object, and action with each term originating from one of 22 biological ontologies (Ives, et al., 2017; See List). Biological process describes dynamics of the underlying biological system (e.g., receptor signalling). 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 signalling 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. More help
Process Object Action
androgen biosynthetic process 11-Keto-testosterone decreased

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
PPARa Agonism Impairs Fish Reproduction KeyEvent Ashley Kittelson (send email) Under development: Not open for comment. Do not cite
11β-hydroxylase inhibition, infertility in fish KeyEvent Young Jun Kim (send email) Under development: Not open for comment. Do not cite
11βHSD inhibition, decreased trajectory KeyEvent Young Jun Kim (send email) Under development: Not open for comment. Do not cite


This is a structured field used to identify specific agents (generally chemicals) that can trigger the KE. Stressors identified in this field will be linked to the KE in a machine-readable manner, such that, for example, a stressor search would identify this as an event the stressor can trigger. NOTE: intermediate or downstream KEs in one AOP may function as MIEs in other AOPs, meaning that stressor information may be added to the KE description, even if it is a downstream KE in the pathway currently under development.Information concerning the stressors that may trigger an MIE can be defined using a combination of structured and unstructured (free-text) fields. For example, structured fields may be used to indicate specific chemicals for which there is evidence of an interaction relevant to this MIE. By linking the KE description to a structured chemical name, it will be increasingly possible to link the MIE to other sources of chemical data and information, enhancing searchability and inter-operability among different data-sources and knowledgebases. The free-text section “Evidence for perturbation of this MIE by stressor” can be used both to identify the supporting evidence for specific stressors triggering the MIE as well as to define broad chemical categories or other properties that classify the stressors able to trigger the MIE for which specific structured terms may not exist. More help

Taxonomic Applicability

Latin or common names of a species or broader taxonomic grouping (e.g., class, order, family) can be selected from an ontology. 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
teleost fish teleost fish High NCBI
Order carcharhiniformes carcharhiniformes Moderate NCBI
mammals mammals Low NCBI

Life Stages

The structured ontology terms for life-stage are more comprehensive than those for taxa, but may still require further description/development and explanation in the free text section. More help
Life stage Evidence
Juvenile Moderate
Adult, reproductively mature High
larvae Moderate

Sex Applicability

No help message More help
Term Evidence
Male High
Female High

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. For example, the biological state being measured could be the activity of an enzyme, the expression of a gene or abundance of an mRNA transcript, the concentration of a hormone or protein, neuronal activity, heart rate, etc. The biological compartment may be a particular cell type, tissue, organ, fluid (e.g., plasma, cerebrospinal fluid), etc. The role in the biology could describe the reaction that an enzyme catalyses and the role of that reaction within a given metabolic pathway; the protein that a gene or mRNA transcript codes for and the function of that protein; the function of a hormone in a given target tissue, physiological function of an organ, etc. Careful attention should be taken to avoid reference to other KEs, KERs or AOPs. Only describe this KE as a single isolated measurable event/state. This will ensure that the KE is modular and can be used by other AOPs, thereby facilitating construction of AOP networks. More help

11-ketotestosterone (11KT) is the dominant androgen in teleost fish. It is synthesized from testosterone using the enzymes CYP11b1 and HSD11b (Yazawa et al., 2008; Swart et al., 2013).

Zebrafish studies also show that cyp17a1 and cyp11c1 knockouts have dramatically reduced levels of 11KT (Shu et al., 2020; Zhang et al., 2020)

Although mutations in the mettl3 gene usually cause embryonic lethality, one particular mutation in non-lethal and causes significantly reduced 11KT levels in zebrafish (Xia et al., 2018)

How It Is Measured or Detected

One of the primary considerations in evaluating AOPs is the relevance and reliability of the methods with which the KEs can be measured. The aim of this section of the KE description is not to provide detailed protocols, but rather to capture, in a sentence or two, per method, the type(s) of measurements that can be employed to evaluate the KE and the relative level of scientific confidence in those measurements. Methods that can be used to detect or measure the biological state represented in the KE should be briefly described and/or cited. 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).Key considerations regarding scientific confidence in the measurement approach include whether the assay is fit for purpose, whether it provides a direct or indirect measure of the biological state in question, whether it is repeatable and reproducible, and the extent to which it is accepted in the scientific and/or regulatory community. Information can be obtained from the OECD Test Guidelines website and the EURL ECVAM Database Service on Alternative Methods to Animal Experimentation (DB-ALM). ?

11KT production can be measured in an ex vivo steroidogenesis assay using the organism's gonad after it has been exposed to a compound.

The concentration of 11KT can be measured in a radioimmunoassay or enzyme-linked immunosorbent assay (ELISA). 

Several papers show that in fish, 11KT is correlated with testosterone levels (Spanò et al., 2004; Maclatchy & Vanderkraak, 1995; Lorenzi et al., 2008). 

Domain of Applicability

This free text section should be used to elaborate on the scientific basis for the indicated domains of applicability and the WoE calls (if provided). While structured terms may be selected to define the taxonomic, life stage and sex applicability (see structured applicability terms, above) of the KE, the structured terms may not adequately reflect or capture the overall biological applicability domain (particularly with regard to taxa). Likewise, the structured terms do not provide an explanation or rationale for the selection. The free-text section on evidence for taxonomic, life stage, and sex applicability can be used to elaborate on why the specific structured terms were selected, and provide supporting references and background information.  More help

Taxanomic Applicability: Most understand of 11KT comes from studies involving teleost fish as it is their dominant androgen. Some studies have measured 11KT in sharks of the order carcharhiniformes, but there is less research in this area (Manire et al., 1999; Garnier et al. 1999; Mills et al. 2010). Many mammals possess the genes necessary to produce 11KT (NCBI), but 11KT may not be as relevant when it’s not the dominant androgen.

Sex Applicability: Males and females use the same biological processes to produce steroids. However, sexual dimorphism in 11KT production varies between species. In humans, plasma levels of 11KT do not differ between sexes (Imamichi et al., 2016). In Zebrafish, gonad levels of 11KT are approximately two magnitudes higher in males than females (Wang & Orban, 2007). Of the 30 other fish species sampled by Lokman et al. (2002), 11KT levels are typically dramatically lower in females than in males, but a few species of the order Perciformes show no sexual dimorphism.

Life Stage Applicability: 11KT can be measured in fish larvae however individuals must be pooled for sufficient sample size (Hattori et al., 2009). Lokman et al. (2002) measured plasma levels of 11-KT in several species of juvenile and adult fish. 11KT levels tend to be higher in males although some fish species don’t show sexual dimorphism. Levels of 11KT in juveniles are similar to levels in females regardless of if the species shows sexual dimorphism in 11KT levels. In males, 11KT increases for spawning and decreases afterwards (Kindler et al., 1989; Páll et al., 2002). Because of it’s involvement in reproduction, 11KT levels may not be meaningful in juveniles.

Evidence for Perturbation by Stressor


Beta-sitosterol causes a dose-depended reduction in 11KT in male goldfish (MacLatchy & Van Der Kraak 1995)


Bezafibrate reduces 11-KT in the plasma of adult male zebrafish (Velasco-Santamaría et al. 2011)


Gemfibrozil reduced 11KT in the plasma of adult male medaka (Lee et al. 2019)

Gemfibrozil expsoure caused reduced 11KT in the testes, plasma, and whole-body samples of adult male zebrafish (Fraz et al., 2018)

Bis(2-ethylhexyl) phthalate

A review of androgen signaling in fish cites several studies showing DEHP decreased 11KT (Golshan et al., 2019)


Cypermethrin causes decreased 11KT in catfish (Singh & Singh, 2008)


Carbamazepine decreased 11KT in the testes, plasma, and whole-body samples of adult male zebrafish (Fraz et al., 2018)


List of the literature that was cited for this KE description. Ideally, the list of references, should conform, to the extent possible, with the OECD Style Guide ( (OECD, 2015). More help

Fraz, S. et al. (2018) “Gemfibrozil and carbamazepine decrease steroid production in zebrafish testes (Danio rerio)”, Aquatic Toxicology, Vol. 198, Elsevier, pp. 1-9. 

Golshan, M. & S.M.H. Alvai (2019) “Androgen signaling in male fishes: Examples of anti-androgenic chemicals that cause reproductive disorders”, Theriogenology, Vol. 139, Elsevier, pp. 58-71. 

Hattori, R.S. et al. (2009) “Cortisol-induced masculinization: Does thermal stress affect gonadal fate in pejerrey, a teleost fish with temperature-dependent sex determination?”, PLoS ONE, Vol. 4(8), pp. 1-7. doi:10.1371/journal.pone.0006548

Imamichi, Y. et al. (2016) “11-Ketotestosterone is a major androgen produced in human gonads”, The Journal of Clinical Endocrinology & Metabolism, Vol. 101(10), Oxford Academic, pp. 3582-3591.

Kindler, P. M. et al. (1989) “Serum 11-ketotestosterone and testosterone concentrations associated with reproduction in male bluegill (Lepomis macrochirus: Centrarchidae)”, General and Comparative Endocrinology, Vol. 75(3), Elsevier, pp. 446-453.

Lee, G. et al. (2019) “Effects of gemfibrozil on sex hormones and reproduction related performances of Oryzias latipes following long-term (155 d) and short-term (21 d) exposure”, Ecotoxicology and Environmental Safety, Vol. 173, Elsevier, pp. 174-181.

Lokman, P.M. et al. (2002) “11-Oxygenated androgens in female teleosts: prevalence, abundance, and life history implications”, General and Comparative Endocrinology, Vol. 129, Academic Press, pp. 1-12. doi: 10.1016/s0016-6480(02)00562-2

Lorenzi, V. et al. (2008) “Diurnal patterns and sex differences in cortisol, 11-ketotestosterone, testosterone, and 17β-estradiol in the bluebanded goby (Lythrypnus dalli)”, General and Comparative Endocrinology, Vol. 155(2)., Elsevier, pp. 438-446.

MacLatchy, D.L. and G.J. Vanderkraak (1995) “The phytoestrogen β-sitosterol alters the reproductive endocrine status of goldfish”, Toxicology and Applied Pharmacology, Vol. 134(2), Elsevier, pp. 305-312.

Manire, C.A., L.E. Rasmussen & T.S. Gross (1999) “Serum steroid hormones including 11-ketotestosterone, 11-ketoandrostenedione, and dihydroprogesterone in juvenile and adult bonnethead sharks, Sphyrna tiburo”, Journal of Experimental Zoology, Vol. 284(5), Wiley-Blackwell, pp. 595-603. DOI: 10.1002/(sici)1097-010x(19991001)284:5<595::aid-jez15> 

Páll, M. K., I. Mayer and B. Borg (2002) “Androgen and behavior in the male three-spined stickleback, Gasterosteus aculeatus I. – Changes in 11-ketotestosterone levels during nesting cycle”, Hormones and Behavior, Vol. 41(4), Elsevier, pp. 377-383.

Shu, T. et al. (2020) “Zebrafish cyp17a1 knockout reveals that androgen-mediated signaling is important for male brain sex differentiation”, General and Comparative Endocrinology, Vol. 295. doi:10.1016/j.ygcen.2020.113490 

Singh, P.B. & V. Singh (2008) “Cypermethrin induced histological changes in gonadotrophic cells, liver, gonads, plasma levels of estradiol-17beta and 11-ketotestosterone, and sperm motility in Heteropneustes fossilis (Bloch)”, Chemosphere, Vol. 72(3), Elsevier, pp. 422-431. DOI: 10.1016/j.chemosphere.2008.02.026 

Spanó, L. et al. (2004) “Effects of atrazine on sex steroid dynamics, plasma vitellogenin concentration and gonad development in adult goldfish (Carassius auratus)”, Aquatic Toxicology, Vol. 66(4), Elsevier, pp. 369-379.

Swart, A.C. et al. (2013) “11β-hydroxyandrostenedione, the product of androstenedione metabolism in the adrenal, is metabolized in LNCaP cells by 5α-reductase yielding 11β-hydroxy-5α-androstanedione”, The Journal of Steroid Biochemistry and Molecular Biology, Vol 138, Elsevier, pp. 132-142.

Velasco-Santamaría, Y.M. et al. (2011) “Bezafibrate, a lipid-lowering pharmaceutical, as a potential endocrine disruptor in male zebrafish (Danio rerio)”, Aquatic Toxicology, Vol. 105, Elsevier, pp. 107-118. doi:10.1016/j.aquatox.2011.05.018

Wang, X.G. and L. Orban (2007) “Anti-Müllerian hormone and 11β-hydroxylase show reciprocal expression to that of aromatase in the transforming gonad of zebrafish males”, Developmental Dynamics, Vol 236(5), Wiley-Liss, pp. 1329-1338.

Xia, H. et al. (2018) “Mettl3 mutation disrupts gamete maturation and reduced fertility in zebrafish”, Genetics, Vol. 208(2), Genetics Society of America, pp. 729-743. DOI: 10.1534/genetics.117.300574 

Yazawa, T. (2008) “Cyp11b1 is induced in the murine gonad by luteinizing hormone/human chorionic gonadotropin and involved in the production of 11-ketotestosterone, a major fish androgen: Conservation and evolution of the androgen metabolic pathway”, Endocrinology, Vol. 149(4), Oxford Academy, pp. 1786-1792.

Zheng, Q. et al. (2020) “Loss of cyp11c1 causes delayed spermatogenesis due to the absence of 11-ketotestosterone", Journal of Endocrinology, Vol. 244(3), Bioscientifica, pp. 487-499.