PM11 Wildlife Ecotoxicology
Exhibit Hall
8:00 AM - Monday
(PM196) Signs of 2,3,7,8-Tetrachlorodibenzo-p-dioxin Exposure in adult Large Japanese Field Mice.
Ohtani, S1, Ozaki, K2, Hoshi, H3, Ishizuka, Y1, Kawai, Y1, Fujita, T1, Shimada, T4, Miyabara, Y5, Tohyama, C6, Nishimura, K1, 1 Agricultural, Food and Environmental Sciences Research Center of Osaka Prefecture, Habikino, Osaka, Japan2 Setsunan University, Hirakata, Osaka, Japan3 Osaka Prefecture University, Sakai, Osaka, Japan4 Forestry and Forest Products Research Institute, Kyoto, Kyoto, Japan5 Shinshu University, Suwa, Nagano, Japan6 National Institute for Environmental Studies, Tsukuba, Ibaragi, Japan
ABSTRACT- The toxicity of dioxins to terrestrial wildlife has not been adequately described to as a means to monitor contamination exposure. Previously we have reported the effects of environmental exposure of dioxins on Large Japanese field mice (Apodemus speciosus)(SETAC North America 2002). In this study, we evaluated the toxicity of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) during a 13-week study using 31 adult Large Japanese field mice born in our laboratory from wild-caught females. In addition to histopathology, evaluations included hematology, plasma testosterone analysis, and CYP1A1 mRNA expression. Groups of 4 to 6 mice of each sex were exposed to TCDD 1 day a week for 13 weeks at doses of 0, 1 or 10 micro g/kg. In male mice exposed to 10 micro g/kg TCDD, a decrease in body weight gain, and an increase in kidney relative weight was observed. Additionally, an increase in liver relative weight in the 1 and 10 micro g/kg TCDD groups were observed. In female mice, a decrease in heart relative weight in the 10 micro g/kg TCDD group, and an increase in liver relative weight in the 1 and 10 micro g/kg TCDD groups were also observed. The concentrations of plasma GPT were significantly higher in TCDD dose groups than in control group. Hepatocyte hypertrophy, solitary hepatocyte necrosis, and eosinophilic globule in the TCDD dose groups were increased significantly. Slight atrophy in spleen and thymus were observed in some animals in TCDD dose groups. There were no significant differences in plasma testosterone concentrations and the CYP1A1 mRNA expression in the livers between dose groups (Control vs. TCDD). These effects in the Large Japanese field mice after exposure to TCDD indicate that these mice are sensitive to TCDD as displayed by a TCDD dependent enlargement of the liver and increase in plasma GPT.
Key words: dioxin, wild mice, histopathology, CYP1A1