Conversion of thyroxine into tri-iodothyronine in zinc deficient rat liver.
Hepatic thyroxine (T4) to tri-iodothyronine (T3) conversion was measured in six animal groups: Group A was fed a severe zinc-deficient diet (1.98 ppm) for 5 weeks; group B was a pair-fed control group for group A; group C was fed a less severe zinc-deficient diet (6.10 ppm) for 5 weeks; group D was a pair-fed control group for group C; group E was fed a zinc-supplemented control diet (90.4 ppm) for 5 weeks; and group F was first fed the severe zinc-deficient diet for 5 weeks and then placed on the zinc-supplemented control diet until a body weight corresponding to the final weight of group E was obtained. Serum T3 and T4 levels and T4 to T3 conversion were significantly reduced in group A. A significant positive correlation was observed between T4 to T3 conversion and alcohol dehydrogenase (zinc-metalloenzyme) activity in liver tissue from the six groups. Thus, it appeared that an appropriate amount of zinc might be one of the factors in thyroxine to tri-iodothyronine conversion in liver tissue normally.
D000426:Alcohol Dehydrogenase / Q000378:metabolism; D000818:Animals; D001835:Body Weight; D004435:Eating; D008099:Liver / Q000201:enzymology / Q000378:metabolism*; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D013974:Thyroxine / Q000097:blood / Q000378:metabolism*; D014284:Triiodothyronine / Q000096:biosynthesis* / Q000097:blood; D015032:Zinc / Q000172:deficiency* / Q000378:metabolism
D014284:Triiodothyronine; D000426:Alcohol Dehydrogenase; D015032:Zinc; D013974:Thyroxine