Alterations in Thyroid Function in Female Sprague-Dawley Rats Following Chronic Treatment with 2,3,7,8-Tetrachlorodibenzo-p-dioxin

Thyroid Lesions in the Great Cormorant (Phalacrocorax carbo) of Niigata, Central Japan: A Possible Association with Dioxin Accumulation

“…In conclusion, our results support previously reported results from the Great Cormorant (Saita et al, 2004;Nakagawa and Niizuma, 2006) and other wild animals (Grassle and Biessmann, 1982;Brouwer et al, 1989;Sewall et al, 1995;Hoffman et al, 1996;Fowles et al, 1997;Kobayashi et al, 2005) by providing detailed histopathologic evidence correlating organochlorine pollution and thyroid lesions in the wildlife of Japan.…”

“…Similar changes in thyroids have also been found in other wild animals, e.g., a euryhaline teleost (Zhou et al, 1999) and marine mammals (Schumacher et al, 1993;Guise et al, 1995). In experimental studies involving organochlorine-exposed rats (Sewall et al, 1995), common seal (Phoca vitulina, Brouwer et al, 1989), American Kestrels (Falco sparverinus, Hoffman et al, 1996), Mallards (Anas platyrhynchos, Fowles et al, 1997), and Japanese Quail (Coturnix japonica, Grassle and Biessmann, 1982), morphologic changes were reported in thyroid glands as well as signs of immunosuppression and drastically reduced levels of circulating retinol and thyroid hormone. Furthermore, various data obtained in a recent study on Jungle Crows (Corvus macrorhynchos) in urban and suburban Tokyo (Kobayashi et al, 2005) strongly suggested an etiologic connection between dioxins and thyroid lesions.…”

“…Concerning this subject, effects of hydroxylated metabolites of PCBs should be specially noted because they are structurally similar to thyroxine (T4) and possibly alter thyroid hormone status by being bound to plasma thyroid hormone-binding proteins (Sandau et al, 2002), disrupting thyroid hormone-mediated neuronal development (Kimura-Kuroda et al, 2007). This mechanism may explain the lesions observed in thyroid glands that were previously reported in various wild animals (Grassle and Biessmann, 1982;Brouwer et al, 1989;Sewall et al, 1995;Hoffman et al, 1996;Fowles et al, 1997;Kobayashi et al, 2005) and in the present case.…”

Implications for risk assessment of suggested nongenotoxic mechanisms of chemical carcinogenesis.

“…This peptide was treated as the induced growth factor in the model of Kohn et al (98). TCDD induces TGF-a in tissues such as keratinocytes (107) Increases in UGT-1 mRNA and alterations in T4 and TSH as described above have been observed in rats given biweekly oral doses of TCDD for 31 weeks (115). Such treatment results in increased serum TSH levels and in concomitant hypertrophy of thyroid follicular cells and thyroid hyperplasia (115).…”

Environmental Thyroid Disruptors and Human Endocrine Health

“…Perchlorate discharge test is also used as in vivo method for determining thyroid toxicity through TR (Atterwill et al, 1987). Finally, another ex vivo parameter is hepatic UDP-GT activity (a marker of enhanced TH clearance form serum) (Barter & Kòaassen, 1994;Kohn et al, 1996;Okazaki & Katayama, 2003;Sewall et al, 1995). On the other hand, many TDs that directly act on the TRs, may produce variable and perhaps unpredicted effects on the TH target tissues (Zoeller, 2005).…”