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  2. Octinoxate as a potential thyroid hormone disruptor - A combination of in vivo and in vitro data

Octinoxate as a potential thyroid hormone disruptor - A combination of in vivo and in vitro data

  • Sci Total Environ. 2023 Jan 15;856(Pt 1):159074. doi: 10.1016/j.scitotenv.2022.159074.
Jana Cahova 1 Jana Blahova 2 Jan Mares 3 Nikola Hodkovicova 4 Pavel Sauer 5 Hana Kocour Kroupova 5 Zdenka Svobodova 1
Affiliations

Affiliations

  • 1 Department of Animal Protection and Welfare and Veterinary Public Health, Faculty of Veterinary Hygiene and Ecology, University of Veterinary Sciences Brno, Czech Republic.
  • 2 Department of Animal Protection and Welfare and Veterinary Public Health, Faculty of Veterinary Hygiene and Ecology, University of Veterinary Sciences Brno, Czech Republic. Electronic address: blahovaj@vfu.cz.
  • 3 Department of Zoology, Fisheries, Hydrobiology and Apiculture, Faculty of AgriSciences, Mendel University in Brno, Czech Republic.
  • 4 Department of Infectious Diseases and Preventive Medicine, Veterinary Research Institute, Brno, Czech Republic.
  • 5 University of South Bohemia in České Budějovice, Faculty of Fisheries and Protection of Waters, South Bohemian Research Center of Aquaculture and Biodiversity of Hydrocenoses, Vodňany, Czech Republic.
Abstract

Ultraviolet filters are commonly used in various cosmetic products. Due to their huge consumption ultraviolet filters become a part of the environment. Octinoxate is a commonly used ultraviolet filter that is widely detected in the aquatic environment. In our study, we investigated whether this ultraviolet filter is able to disrupt thyroid hormone regulation after six weeks of exposure in rainbow trout (Oncorhynchus mykiss). Thyroid Hormones play crucial role in development and regulation of the organism and its disruption could cause the whole-body imbalance. Our study includes a compilation of in vivo and in vitro tests. The results of the in vivo experiment revealed a significant increase in thyroxine hormone in plasma for the highest tested dose of octinoxate (i.e. 395.6 μg/kg). We examined selected tissues (liver and cranial kidney) to determine the mRNA expression of genes involved in thyroid Hormones regulation. The analysis confirmed downregulation of deiodinase 2 mRNA expression for the highest tested dose (i.e. 395.6 μg/kg) and downregulation of paired box 8 mRNA for medium (96 μg/kg) and the highest octinoxate dose (395.6 μg/kg.) only in cranial kidney. In vitro analysis indicated that octinoxate does not elicit (anti-)thyroid activity via thrβ and does not behave as a transthyretin ligand. Based on our results, octinoxate has a potential to act as a thyroid hormone disruptor, but further research required to better understand the entire regulatory mechanism.

Keywords

Fish; Gene expression; Oncorhynchus mykiss; Thyroxine; UV filter.

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