This Article Full Text Full Text (PDF) All Versions of this Article: 148/6/2835    most recent Author Manuscript (PDF) Purchase Article View Shopping Cart Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Copyright Permission Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Schmutzler, C. Articles by Köhrle, J. Search for Related Content PubMed PubMed Citation Articles by Schmutzler, C. Articles by Köhrle, J. Pubmed/NCBI databases Gene GEO Profiles HomoloGene Nucleotide Protein UniGene Compound via MeSH Substance via MeSH Hazardous Substances DB HYDROGEN PEROXIDE IODINE

The Ultraviolet Filter Benzophenone 2 Interferes with the Thyroid Hormone Axis in Rats and Is a Potent in Vitro Inhibitor of Human Recombinant Thyroid Peroxidase

Institut für Experimentelle Endokrinologie (C.Schm., A.B., I.G., K.H., J.K.), Institut für Experimentelle Pädiatrische Endokrinologie (P.A., A.G.), Charité Universitätsmedizin Berlin, D-10117 Berlin, Germany; Klinische und Experimentelle Endokrinologie (H.K., C.Schl., W.W., H.J.), Universitäts-Frauenklinik Göttingen, D-37075 Göttingen, Germany; and Experimentelle und Chirurgische Onkologie (C.H.-V.), Martin-Luther-Universität Halle/Wittenberg, D-06120 Halle/Saale, Germany

Address all correspondence and requests for reprints to: Cornelia Schmutzler, Institut für Experimentelle Endokrinologie, Charité Universitätsmedizin Berlin, Charitéplatz 1, D-10117 Berlin, Germany. E-mail: cornelia.schmutzler{at}charite.de.

Endocrine disrupting chemicals (EDCs), either plant constituents or contaminants deriving from industrial products, may interfere with the thyroid hormone (TH) axis. Here, we examined whether selected EDCs inhibit the key reactions of TH biosynthesis catalyzed by thyroid peroxidase (TPO). We used a novel in vitro assay based on human recombinant TPO (hrTPO) stably transfected into the human follicular thyroid carcinoma cell line FTC-238. F21388 (synthetic flavonoid), bisphenol A (building block for polycarbonates), and the UV filter benzophenone 2 (BP2) inhibited hrTPO. BP2 is contained in numerous cosmetics of daily use and may be in regular contact with human skin. Half-maximal inhibition in the guaiacol assay occurred at 450 nmol/liter BP2, a concentration 20- and 200-fold lower than those required in case of the TPO-inhibiting antithyroid drugs methimazole and propylthiouracil, respectively. BP2 at 300 nmol/liter combined with the TPO substrate H₂O₂ (10 µmol/liter) inactivated hrTPO; this was, however, prevented by micromolar amounts of iodide. BP2 did not inhibit iodide uptake into FRTL-5 cells. In BP2-treated rats (333 and 1000 mg/kg body weight), serum total T₄ was significantly decreased and serum thyrotropin was significantly increased. TPO activities in the thyroids of treated animals were unchanged, a finding also described for methimazole and propylthiouracil. Thus, EDCs, most potently BP2, may disturb TH homeostasis by inhibiting or inactivating TPO, effects that are even more pronounced in the absence of iodide. This new challenge for endocrine regulation must be considered in the context of a still prevailing iodide deficiency in many parts of the world.