We previously observed a rapid reduction in plasma ceruloplasmin activity in lean Zucker (Fa/Fa) rats fed a marginal copper (Cu)-deficient diet compared to similarly fed obese Zucker (fa/fa) and lean Sprague-Dawley rats. In an effort to understand the mechanisms underlying this response, we utilized the isotope dilution method to investigate the absorption and excretion of Cu in lean Zucker rats fed control and marginal Cu diets. Sprague-Dawley (SD) and homozygous lean Zucker rats were fed either a Cu-adequate (Cont; 7.5 μg Cu/g diet) or a low Cu (Low; 1.1 μg Cu/g diet) casein-based diet for 23 d. Two weeks following initiation of the dietary treatment, each rat was injected intramuscularly (im) with 11.2 μCi of67Cu. Urine and feces were collected daily. On the 9th d following isotope injection, rats were killed and tissues collected. Significant dietary effects were observed in the relative absorption and endogenous fecal excretion of67Cu. The tissue distributions of nonisotopic Cu and67Cu activity were also different between dietary treatments. Tissues from rats fed the low-Cu diet typically had high concentrations of67Cu and low concentrations of nonisotopic Cu compared to controls. An increase in relative67Cu absorption was evident for rats fed the low-Cu diet (57.2 and 39.3%, for SD Low, Zucker Low, respectively, and 17.9, and 28.5% SD Cont and Zucker Cont, respectively). Rats fed the low-Cu diet also had reductions in endogenous fecal excretion of67Cu compared to their respective controls. Although strain effects were not evident for either percent Cu absorption or endogenous fecal Cu excretion, the relative adaptive changes appeared more marked for the Sprague-Dawley rats compared to the lean Zucker rats.
ASJC Scopus subject areas
- Endocrinology, Diabetes and Metabolism
- Biochemistry, medical
- Inorganic Chemistry
- Clinical Biochemistry
- Biochemistry, Genetics and Molecular Biology(all)