1. Toxicology DivisionInstitute of Environmental Toxicology 4321, Uchimoriya‐machi Joso‐shi Ibaraki 303‐0043 Japan
2. Laboratory of Veterinary Pharmacology, School of Veterinary MedicineAzabu University 1‐17‐71 Fuchinobe, Chuo‐ku Sagamihara‐shi Kanagawa 252‐5201 Japan