| Co-Investigator(Kenkyū-buntansha) |
FUJIMOTO Nariaki Hiroshima University, Research Institute for Radiation Biology and Meddicine, Associate Professor, 原爆放射線医科学研究所, 助教授 (40243612)
KASHIWAGI Akihiko Hiroshima University, Graduate School of Science, Professor, 大学院・理学研究科, 教授 (50106796)
OHTA Shigeru Hiroshima University, Graduate School of Biomedical Sciences, Professor, 大学院・医歯薬学総合研究科, 教授 (60160503)
SUGIHARA Kazumi Hiroshima University, Faculty of Medicine, Research Associate, 医学部, 教務員 (20271067)
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| Research Abstract |
The thyroid hormone-disrupting activity of bisphenol A derivatives and some PCBs was estimated by the reporter assay using a rat pituitary cell line (GH3) and a Chinese hamster ovary cell line (CHO-K1). Tetrabromobisphenol A (TBBPA), tetrachlorobisphenol A, 4-hydroxy-2,2',3,4',5,5'-hexachiorobiphenyl, 4-hydroxy-3,3',4',5-tetrachlorobiphenyl and 4,4'-dihydroxy-3,3',5,5'-tetrachlorobiphenyl showed thyroid hormonal effect on GH3 cells. However, 4-hydroxy-2,2',5,5'-tetrachlorobiphenyl, 4-hydroxy-2',4',6'-trichlorobiphenyl, 3-hydroxy-2,2',5,5'-tetrachlorobiphenyl, 2,3',5,5'-tetrachlorobiphenyl and bisphenol A did not exhibit the activity. Especially, TBBPA, a flame retardant, exhibited the highest thyroid hormonal activity. In contrast, these chemicals showed anti-thyroid hormone effects on the activity of triiodothyronine (T3) in CHO-K1 cells transfected with thyroid hormone receptor (TR). 3,5-Substituted bromide or chlorine is an essential factor for the thyroid hormone-disrupting activity. The action of these chemicals was also estimated by amphibian metamorphosis using tadpole. The tail of tadpole was shortened by the addition of T3. These chemicals showed antagonistic effect on the T3-induced tadpole tail regression. These facts suggest that a brominated flame retardant, TBBPA, and hydroxylated PCBs exhibit endocrine-disrupting action in the wildlife.
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