Effect of low zinc diet on (65)Zn turnover in non-insulin dependent diabetic mice

To investigate the effect of low-Zn diet on (65)Zn turnover and content in non-insulin dependent diabetes (NIDDM).

Male 8-9 weeks old, genetically diabetic mice (C57BL/KsJdb/db) and non-diabetic heterozygote litter-mates (C57BL/KsJdb/+) were fed on a diet containing 1 mg zinc/kg (low-zinc groups) or 54 mg zinc/kg (control groups), and injected subcutaneously with (65)Zn. Body weight gain was recorded regularly, whereas (65)Zn body loss was measured by whole-body counting in the two mouse genotypes over a 28 days period. At the end of the experiment, pancreatic Zn, femur Zn and non-fasting blood glucose levels were determined.

All mice fed on the low-Zn diet showed a marked reduction in whole-body (65)Zn loss compared with animals fed on the control diet. In the low Zn groups, the loss of (65)Zn from the diabetic mice was significantly greater than that of heterozygote mice. This difference was not observed in the control groups. Body-weight gain was not affected by low zinc diet for the two genotypes. However, blood glucose levels were elevated in the low-Zn groups and the possible reasons for these observations are discussed.

The present study demonstrates that there is almost a dramatic decrease in (65)Zn turnover rate immediately following the introduction of the low zinc diet to the animals, but the diabetic mice were less able to reduce zinc loss compared to non diabetic ones. It was also found that the effect of reduced zinc intake on glucose utilization in the genetically diabetic mouse, occurred before any significant tissue zinc depletion became apparent.