Effect of thyroidectomy and thyroxine on 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) induced toxicity.
Chemical thyroidectomy effectively protected athyroid rats from mortality during 45 days after dosing with 100 micrograms 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)/kg, whereas 70 to 80% of nonthyroidectomized-euthyroid and thyroidectomized-T4 (thyroxine)-maintained-euthyroid rats died within the same period of time. There was a significant decrease in body weight of all TCDD-treated groups compared to vehicle controls. However, body weight loss was much slower in thyroidectomized-athyroid (congruent to 1 g/day) than in nonthyroidectomized-euthyroid or in thyroidectomized-T4-euthyroid (congruent to 8 g/day) rats. TCDD significantly reduced feed intake in nonthyroidectomized-euthyroid and thyroidectomized-T4-euthyroid rats, but no altered feed consumption was observable in thyroidectomized-athyroid animals. These data indicate that thyroid hormone(s) play(s) an important role in mediating the toxicity of TCDD.
D000818:Animals; D001835:Body Weight / Q000187:drug effects; D004147:Dioxins / Q000633:toxicity*; D004435:Eating; D008297:Male; D000072317:Polychlorinated Dibenzodioxins / Q000633:toxicity*; D051381:Rats; D011919:Rats, Inbred Strains; D013950:Thymus Gland / Q000187:drug effects; D013961:Thyroid Gland / Q000502:physiology*; D013965:Thyroidectomy; D013974:Thyroxine / Q000097:blood*; D014284:Triiodothyronine / Q000097:blood
D004147:Dioxins; D000072317:Polychlorinated Dibenzodioxins; D014284:Triiodothyronine; D013974:Thyroxine