Conversion of thyroxine into tri-iodothyronine in zinc deficient rat liver

J Pediatr Gastroenterol Nutr. 1986 Sep-Oct;5(5):799-805. doi: 10.1097/00005176-198609000-00023.

Abstract

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.

MeSH terms

  • Alcohol Dehydrogenase / metabolism
  • Animals
  • Body Weight
  • Eating
  • Liver / enzymology
  • Liver / metabolism*
  • Male
  • Rats
  • Rats, Inbred Strains
  • Thyroxine / blood
  • Thyroxine / metabolism*
  • Triiodothyronine / biosynthesis*
  • Triiodothyronine / blood
  • Zinc / deficiency*
  • Zinc / metabolism

Substances

  • Triiodothyronine
  • Alcohol Dehydrogenase
  • Zinc
  • Thyroxine