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Hepatotoxic effects of cyproconazole and prochloraz in wild-type and hCAR/hPXR mice

Archives of Toxicology volume 91, pages 2895–2907 (2017)Cite this article

Abstract

The agricultural fungicides cyproconazole and prochloraz exhibit hepatotoxicity in rodent studies and are tumorigenic following chronic exposure. Both substances are suspected to act via a CAR (constitutive androstane receptor)/PXR (pregnane-X-receptor)-dependent mechanism. Human relevance of these findings is under debate. A 28-day toxicity study was conducted in mice with humanized CAR and PXR (hCAR/hPXR) with two dose levels (50 or 500 ppm) of both substances, using the model CAR activator phenobarbital as a reference. Results were compared to wild-type mice. A treatment-related increase in liver weights was observed for all three substances at least at the high-dose level. Changes in the expression of classic CAR/PXR target genes such as Cyp2b10 were induced by cyproconazole and phenobarbital in both genotypes, while prochloraz treatment resulted in gene expression changes indicative of additional aryl hydrocarbon receptor activation, e.g. by up-regulation of Cyp1a1 expression. Cyproconazole-induced effects on CAR-dependent gene expression, liver weight, and hepatic lipid accumulation were more prominent in wild-type mice, where significant genotype differences were observed at the high-dose level. Moreover, high-dose cyproconazole-treated mice from the wild-type group responded with a marked increase in hepatocellular proliferation, while hCAR/hPXR mice did not. In conclusion, our data demonstrate that cyproconazole and PB induce CAR/PXR downstream effects in hepatocytes in vivo via both, the murine and human receptors. At high doses of cyproconazole, however, the responses were clearly more pronounced in wild-type mice, indicating increased sensitivity of rodents to CAR agonist-induced effects in hepatocytes.

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Acknowledgements

The authors greatly acknowledge expert technical assistance by Johanna Mahr, Silvia Vetter, Elke Zabinsky and Barbara Freytag. We also thank Dr. U. Zanger (Stuttgart, Germany) for providing the hCYP2B6 reporter plasmid, Dr. S. Armeanu-Ebinger, Dr. J. Fuchs and Dr. S. Warmann (Tuebingen, Germany) for providing access to HC-AFW1 cells, and Dr. C.R. Wolf (Dundee, UK) for the gift of CYP antisera. This study was supported by the German Federal Institute for Risk Assessment (Grant SFP1322-499).

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Affiliations

  1. Department of Pesticides Safety, German Federal Institute for Risk Assessment, Max-Dohrn-Str. 8-10, 10589, Berlin, Germany

    Philip Marx-Stoelting, Constanze Knebel, Flavia Schmidt & Svenja Rieke

  2. Institute for Biochemistry, Technical University of Berlin, Straße des 17. Juni 153, 10623, Berlin, Germany

    Philip Marx-Stoelting

  3. Department of Toxicology, University of Tübingen, Wilhelmstr. 56, 72074, Tübingen, Germany

    Katrin Ganzenberg, Michael Schwarz & Albert Braeuning

  4. Natural and Medical Sciences Institute at the University of Tübingen, Markwiesenstr. 55, 72770, Reutlingen, Germany

    Helen Hammer, Felix Schmidt & Oliver Pötz

  5. Department of Food Safety, German Federal Institute for Risk Assessment, Max-Dohrn-Str. 8-10, 10589, Berlin, Germany

    Albert Braeuning

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  1. Philip Marx-Stoelting
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  2. Katrin Ganzenberg
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  3. Constanze Knebel
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  4. Flavia Schmidt
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  5. Svenja Rieke
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  6. Helen Hammer
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  7. Felix Schmidt
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  9. Michael Schwarz
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  10. Albert Braeuning
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Correspondence to Albert Braeuning.

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Marx-Stoelting, P., Ganzenberg, K., Knebel, C. et al. Hepatotoxic effects of cyproconazole and prochloraz in wild-type and hCAR/hPXR mice. Arch Toxicol 91, 2895–2907 (2017). https://doi.org/10.1007/s00204-016-1925-2

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  • DOI: https://doi.org/10.1007/s00204-016-1925-2

Keywords

  • Liver
  • Constitutive androstane receptor
  • Aryl hydrocarbon receptor
  • Phenobarbital
  • Cytochrome P450
  • Tumor promotion