کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
2572057 | 1128669 | 2006 | 10 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
A mode of action for induction of thyroid gland tumors by Pyrethrins in the rat
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کلمات کلیدی
موضوعات مرتبط
علوم زیستی و بیوفناوری
علوم محیط زیست
بهداشت، سم شناسی و جهش زایی
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چکیده انگلیسی
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 8000Â ppm Pyrethrins and female rats diets containing 0, 100, 3000 and 8000Â 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 1200-1558Â ppm sodium Phenobarbital (NaPB) for 7 and 14 days. The treatment of male rats with 8000Â ppm Pyrethrins, female rats with 3000 and 8000Â 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). The effects of Pyrethrins in female rats were dose-dependent, with 100Â ppm being a no-effect level, and on cessation of treatment were essentially reversible in both sexes. The concordance between the effects of Pyrethrins and NaPB suggests that the mode of action for Pyrethrins-induced rat thyroid gland tumors is similar to that of some other non-genotoxic inducers of hepatic xenobiotic metabolism.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Toxicology and Applied Pharmacology - Volume 214, Issue 3, 1 August 2006, Pages 253-262
Journal: Toxicology and Applied Pharmacology - Volume 214, Issue 3, 1 August 2006, Pages 253-262
نویسندگان
John M. Finch, Thomas G. Osimitz, Karl L. Gabriel, Tom Martin, Wendy J. Henderson, Charles C. Capen, William H. Butler, Brian G. Lake,