A mode of action for induction of thyroid gland tumors by Pyrethrins in the rat

Toxicology and Applied Pharmacology
John M FinchB G Lake

Abstract

Prolonged treatment with high doses of Pyrethrins results in thyroid gland tumors in the rat. To elucidate the mode of action for tumor formation, the effect of Pyrethrins on rat thyroid gland, thyroid hormone levels and hepatic thyroxine UDPglucuronosyltransferase activity was investigated. Male Sprague-Dawley CD rats were fed diets containing 0 (control) and 8000 ppm Pyrethrins and female rats diets containing 0, 100, 3000 and 8000 ppm Pyrethrins for periods of 7, 14 and 42 days and for 42 days followed by 42 days of reversal. As a positive control, rats were also fed diets containing 1200-1558 ppm sodium Phenobarbital (NaPB) for 7 and 14 days. The treatment of male rats with 8000 ppm Pyrethrins, female rats with 3000 and 8000 ppm Pyrethrins and both sexes with NaPB resulted in increased thyroid gland weights, which were associated with follicular cell hypertrophy. Thyroid follicular cell replicative DNA synthesis was increased by treatment with Pyrethrins and NaPB for 7 and/or 14 days. Treatment with Pyrethrins and NaPB increased hepatic microsomal thyroxine UDPglucuronosyltransferase activity and serum thyroid stimulating hormone levels (TSH), but reduced serum levels of either thyroxine (T4) and/or triiodothyronine (T3). T...Continue Reading

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Citations

Feb 25, 2015·Regulatory Toxicology and Pharmacology : RTP·Sabitha PapineniDavid L Eisenbrandt
May 28, 2011·Thyroid : Official Journal of the American Thyroid Association·Fabrice HerinJean-Marc Soulat
Dec 26, 2006·Toxicology and Applied Pharmacology·Roger J PriceBrian G Lake
Feb 10, 2017·Environmental Toxicology·Golla Madhubabu, Suresh Yenugu
May 1, 2015·Shokuhin eiseigaku zasshi. Journal of the Food Hygienic Society of Japan·Midori YoshidaKoichi Yoshinari
Jul 28, 2016·Drug and Chemical Toxicology·Mohammad AzabLiliana Nassar
May 26, 2009·Critical Reviews in Toxicology·Thomas G Osimitz, Brian G Lake

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