Effect of reduced dietary zinc intake on carbohydrate and Zn metabolism in the genetically diabetic mouse (C57BL/KsJ db+/db+)

1. Male, 4-5-week-old, genetically diabetic mice (C57BL/KsJ db/db) and non-diabetic heterozygote littermates (C57BL/KsJ db/+) were fed on a diet containing 1 mg zinc/kg (low-Zn groups) or 54 mg Zn/kg (control groups) for 27 d. Food intakes and body-weight gain were recorded regularly. On day 28, after an overnight fast, animals were killed and blood glucose and insulin concentrations, liver glycogen, and femur and pancreatic Zn concentrations were determined. 2. The consumption of the low-Zn diet had only a minimal effect on the Zn status of the mice as indicated by growth rate, food intake and femur and pancreatic Zn concentrations. In fact, diabetic mice fed on the low-Zn diet had a higher total food intake than those fed on the control diet. The low-Zn diabetic mice had higher fasting blood glucose and liver glycogen levels than their control counterparts. Fasting blood insulin concentration was unaffected by dietary regimen. 3. A second experiment was performed in which the rate of loss of 65Zn, injected subcutaneously, was measured by whole-body counting in the two mouse genotypes over a 28 d period, from 4 to 5 weeks of age. The influence of feeding low-Zn or control diets was also examined. At the end of the study femur and pancreatic Zn and non-fasting blood glucose levels were determined. 4. All mice fed on the low-Zn diet showed a marked reduction in whole-body 65Zn loss compared with those animals fed on the control diet.(ABSTRACT TRUNCATED AT 250 WORDS)