A1 Journal article (refereed)
Endogenous AhR agonist FICZ accumulates in rainbow trout (Oncorhynchus mykiss) alevins exposed to a mixture of two PAHs, retene and fluoranthene (2022)

Eriksson, A. N. M., Rigaud, C., Wincent, E., Pakkanen, H., Salonen, P., & Vehniäinen, E.-R. (2022). Endogenous AhR agonist FICZ accumulates in rainbow trout (Oncorhynchus mykiss) alevins exposed to a mixture of two PAHs, retene and fluoranthene. Ecotoxicology, 31(9), 1382-1389. https://doi.org/10.1007/s10646-022-02593-9

JYU authors or editors

Publication details

All authors or editorsEriksson, Andreas N. M.; Rigaud, Cyril; Wincent, Emma; Pakkanen, Hannu; Salonen, Pihla; Vehniäinen, Eeva-Riikka

Journal or seriesEcotoxicology



Publication year2022

Publication date11/10/2022


Issue number9

Pages range1382-1389


Publication countryUnited States

Publication languageEnglish


Publication open accessOpenly available

Publication channel open accessPartially open access channel

Publication is parallel published (JYX)https://jyx.jyu.fi/handle/123456789/83525


Multiple studies have reported synergized toxicity of PAH mixtures in developing fish larvae relative to the additive effect of the components. From a toxicological perspective, multiple mechanisms are known to contribute to synergism, such as altered toxicodynamics and kinetics, as well as increased oxidative stress. An understudied contributor to synergism is the accumulation of endogenous metabolites, for example: the aryl hydrocarbon receptor 2 (AhR2) agonist and tryptophan metabolite 6-Formylindolo(3,2-b)carbazole (FICZ). Fish larvae exposed to FICZ, alongside knock-down of cytochrome p450 (cyp1a), has been reported to induced symptoms of toxicity similar to those observed following exposure to PAHs or the dioxin 2,3,7,8-tetrachlorodibenzo-p-dioxin. Here, we explored if FICZ accumulates in newly hatched rainbow trout alevins (Oncorhynchus mykiss) exposed to two PAHs with different properties: retene (potent AhR2 agonist) and fluoranthene (weak AhR2 agonist and Cyp1a inhibitor), either alone or as a binary mixture for 3 and 7 days. We found that exposure to the mixture resulted in accumulation of endogenous FICZ, synergized the blue sac disease index (BSD), and altered the body burden profiles of the PAHs, when compared to the alevins exposed to the individual components. It is thus very plausible that accumulation of endogenously derived FICZ contributed to the synergized BSD index and toxicity in exposed alevins. Accumulation of endogenously derived FICZ is a novel finding that extends our general understanding on PAHs toxicity in developing fish larvae, while at the same time highlighting why environmental risk assessment of PAHs should not be based solely results from the assessment of individual compounds.

Keywordsenvironmental toxinsPAH compoundsfishesrainbow troutembryogenesismetabolic productsecotoxicology

Free keywordssynergism; mixture; PAH; FICZ; Oncorhynchus mykiss; blue sac disease

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Ministry reportingYes

Reporting Year2022

JUFO rating1

Last updated on 2024-15-06 at 01:45