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  • Soy isoflavones interfere with thyroid hormone homeostasis in orchidectomized middle-aged rats.

Soy isoflavones interfere with thyroid hormone homeostasis in orchidectomized middle-aged rats.

Toxicology and applied pharmacology (2014-05-06)
Branka Šošić-Jurjević, Branko Filipović, Eva Katrin Wirth, Jasmina Živanović, Niko Radulović, Snežana Janković, Verica Milošević, Josef Köhrle
ABSTRACT

We previously reported that genistein (G) and daidzein (D) administered subcutaneously (10mg/kg) induce changes in the angio-follicular units of the thyroid gland, reduce concentration of total thyroid hormones (TH) and increase thyrotropin (TSH) in serum of orchidectomized middle-aged (16-month-old) rats. To further investigate these effects, we now examined expression levels of the thyroglobulin (Tg), thyroperoxidase (Tpo), vascular endothelial growth factor A (Vegfa) and deiodinase type 1 (Dio 1) genes in the thyroid; in the pituitary, genes involved in TH feedback control (Tsh β, Dio 1, Dio 2, Trh receptor); and in the liver and kidney, expression of T3-activated genes Dio 1 and Spot 14, as well as transthyretin (Ttr), by quantitative real-time PCR. We also analyzed TPO-immunopositivity and immunofluorescence of T4 bound to Tg, determined thyroid T4 levels and measured deiodinase enzyme activities in examined organs. Decreased expression of Tg and Tpo genes (p<0.05) correlated with immunohistochemical staining results, and together with decreased serum total T4 levels, indicates decreased Tg and TH synthesis following treatments with both isoflavones. However, expression of Spot 14 (p<0.05) gene in liver and kidney was up-regulated, and liver Dio 1 expression and activity (p<0.05) increased. At the level of pituitary, no significant change in gene expression levels, or Dio 1 and 2 enzyme activities was observed. In conclusion, both G and D impaired Tg and TH synthesis, but at the same time increased tissue availability of TH in peripheral tissues of Orx middle-aged rats.

MATERIALS
Product Number
Brand
Product Description

Supelco
Genistein, analytical standard
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Acetic acid, ≥99.5%, FCC, FG
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Acetic acid-12C2, 99.9 atom % 12C
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Genistein, from Glycine max (soybean), ~98% (HPLC)
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N-tert-Butyldimethylsilyl-N-methyltrifluoroacetamide, >97%
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Hematoxylin
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Genistein, synthetic, ≥98% (HPLC), powder
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Acetic acid, natural, ≥99.5%, FG
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Hematoxylin, certified by the Biological Stain Commission
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Acetic acid, glacial, ACS reagent, ≥99.7%
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Acetic acid solution, suitable for HPLC
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Acetic acid, for luminescence, BioUltra, ≥99.5% (GC)
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5α-Androstan-17β-ol-3-one, ≥97.5%
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Acetic acid, glacial, ReagentPlus®, ≥99%
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Acetic acid, glacial, puriss. p.a., ACS reagent, reag. ISO, reag. Ph. Eur., ≥99.8%
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Acetic acid, glacial, puriss., meets analytical specification of Ph. Eur., BP, USP, FCC, 99.8-100.5%
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Acetic acid, glacial, puriss., 99-100%
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Daidzein, ≥98%, synthetic
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Glacial acetic acid, United States Pharmacopeia (USP) Reference Standard
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Acetic acid, glacial, ≥99.99% trace metals basis
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Bifido Selective Supplement B, suitable for microbiology
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Fluorescein, for fluorescence, free acid
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Daidzein, analytical standard
Fluorescein, European Pharmacopoeia (EP) Reference Standard
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5α-Androstan-17β-ol-3-one, VETRANAL®, analytical standard