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Home » Study Results & Research Projects » NTP Study Reports » Short-Term Toxicity Reports and Abstracts » TOX-62 Abstract
Wy-14,643 was selected for inclusion in a series of studies on peroxisome proliferators because it is known to produce considerable peroxisome proliferation and hepatocarcinogenicity in rats. Male Sprague-Dawley rats were exposed to Wy-14,643 (greater than 98% pure) in feed for up to 3 months; male B6C3F1
mice and male Syrian hamsters were exposed to Wy-14,643 in feed for 2 weeks or up to 3 months. Animals were evaluated for clinical pathology, plasma concentrations of Wy-14,643, reproductive system effects, cell proliferation and peroxisomal enzyme analyses, and histopathology. Single and multiple-dose toxicokinetic studies of Wy-14,643 were conducted in additional groups of male Sprague-Dawley and Wistar Furth rats, B6C3F1
mice, and Syrian hamsters. Genetic toxicology studies were conducted
in vivo
in Tg.AC mouse peripheral blood erythrocytes.
In the 2-week studies, groups of five mice were fed diets containing 0, 10, 50, 100, 500, or 1,000 ppm Wy-14,643 (equivalent to average daily doses of approximately 2 to 184 mg Wy-14,643/kg body weight). Groups of five hamsters were fed diets containing 0, 10, 100, 500, 1,000, or 5,000 ppm Wy-14,643 (equivalent to average daily doses of approximately 1 to 550 mg/kg). All animals survived to the end of the studies. The mean body weight gain of 500 ppm mice was significantly less than that of the controls; hamsters exposed to 100 ppm or greater lost weight during the study. Feed consumption by 500 ppm mice was greater than that by the controls. Liver weights of all exposed groups of mice and hamsters were generally significantly increased.
In the 2-week studies, an increase in peroxisomal enzyme activity occurred in 10 ppm mice; increases in peroxisomal beta-oxidation, carnitine acetyltransferase, catalase, and acyl CoA oxidase occurred in all exposed mice compared to controls. Significantly increased BrdU-labeled hepatocyte percentages occurred in 100 and 1,000 ppm mice and 500 and 5,000 ppm hamsters; peroxisomal beta-oxidation of lipids was increased in all exposed groups of mice and hamsters.
Gross lesions in the 2-week studies included liver foci in one 500 ppm mouse and one 1,000 ppm hamster and enlarged livers in one hamster in each of the 100 and 500 ppm groups and two 5,000 ppm hamsters. All 500 and 1,000 ppm mice had hepatocyte hypertrophy of the liver, and 1,000 ppm mice also had widespread individual cell necrosis. Minimal to mild multifocal vacuolation of the liver occurred in hamsters exposed to 500 ppm or greater.
In the 3-month core studies, groups of 10 male rats, mice, or hamsters were fed diets containing 0, 5, 10, 50, 100, or 500 ppm Wy-14,643 (equivalent to average daily doses of approximately 0.3 to 34 mg/kg for rats, 0.9 to 135 mg/kg for mice, and 0.4 to 42 mg/kg for hamsters). Groups of 15 male rats, mice, or hamsters designated for special studies received the same concentrations of Wy-14,643 for up to 13 weeks. Groups of six male rats, 36 male mice, or 12 male hamsters designated for plasma concentration studies were fed diets containing 50, 100, or 500 ppm Wy-14,643 for up to 9 weeks.
Synonyms: [4-Chloro-6-(2,3-xylidino)-2-pyrimidinylthio]acetic acid
Growth & Survival Curves for NTP Short-term Toxicity Studies
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Web page last updated on November 28, 2007
The National Institute of Environmental Health Sciences is one of the National Institutes of Health within the U.S. Department of Health and Human Services. The National Toxicology Program is headquartered on the NIEHS campus in Research Triangle Park, NC.