The effect of experimental hyperthyroidism and hypothyroidism on 5'-monodeiodination of 3,3',5'-triiodothyronine and 3',5'-diiodothyronine by rat liver and kidney.
To study the effect of alterations in thyroid status on 5'-monodeiodinase activity, conversions of rT3 to 3,3'-diiodothyronine and 3',5'-diiodothyronine (3',5'-T2) to 3'-monoiodothyronine were examined in vitro. Rats were injected either with T4 (10 micrograms/100 g BW, ip, daily for 12 days) to make them thyrotoxic or thyroidectomized to render them hypothyroid, and liver and kidney homogenates were prepared. Liver homogenates from hyperthyroid animals demonstrated a 2-fold increase in 5'-monodeiodination of both rT3 and 3',5'-T2; both reactions were also significantly increased in the kidneys of hyperthyroid rats. Hypothyroidism produced a significant decrease in 5'-deiodination of both rT3 and 3',5'-T2 in liver and kidney homogenates. These data indicate that the in vitro 5'-deiodination of both rT3 and 3',5'-T2 is increased in hyperthyroidism and decreased in hypothyroidism and suggest that these two iodothyronines are metabolized in a similar fashion in rat liver and kidney homogenates in states of altered thyroid function.
D000818:Animals; D004104:Diiodothyronines / Q000378:metabolism*; D006980:Hyperthyroidism / Q000139:chemically induced / Q000378:metabolism*; D007037:Hypothyroidism / Q000378:metabolism*; D007455:Iodine / Q000378:metabolism*; D007668:Kidney / Q000378:metabolism; D008099:Liver / Q000378:metabolism; D008297:Male; D051381:Rats; D013965:Thyroidectomy; D013970:Thyronines / Q000378:metabolism*; D013974:Thyroxine; D014284:Triiodothyronine / Q000378:metabolism*; D014285:Triiodothyronine, Reverse / Q000378:metabolism*
D004104:Diiodothyronines; D013970:Thyronines; D014284:Triiodothyronine; C013068:3-monoiodothyronine; D014285:Triiodothyronine, Reverse; D007455:Iodine; D013974:Thyroxine