Effects of zinc and thyroxine treatment on dietary-obese mice.

Altered thyroid hormone metabolism is known to be an important factor contributing to the defective expression of thermogenesis in the obese mouse, and the action of zinc on thyroid hormone conversion may be an important factor in the energy metabolism of obesity. The effects of zinc and thyroxine treatment on dietary-obese mice were examined. The dietary-obese mice were successfully induced by high-fat diet (80% fat), and every mouse was administered daily 1.25 mg zinc sulfate and/or 5 micrograms thyroxine. After 8 weeks of treatment, serum zinc, serum triacylglycerols and body fat composition were determined. On high-fat diets, fat deposition was found in male mice treated with zinc sulfate. However, when mice were treated with zinc and thyroxine at the same time, serum triacylglycerols and body fat composition decreased significantly on both basal and high-fat diets. When mice were treated with thyroxine alone, body fat composition decreased significantly, but there was no significant effect on serum triacylglycerols on either diet. Obesity was significantly correlated with dietary fat, zinc and thyroid hormone. It is suggested that zinc may play an important role, through its action on thyroid hormone conversion and via insulin action, in the energy metabolism of dietary-obese mice.