EFFECT OF INSULIN-TREATMENT OR ZINC SUPPLEMENTATION ON VITAMIN-A STATUS IN STREPTOZOTOCIN-INDUCED DIABETIC RATS

Using streptozotocin-induced diabetic rats, we examined the effects of zinc supplementation and insulin treatment on the metabolic availabil ity of vitamin A. All diabetic animals exhibited an elevated plasma gl ucose (> 18 mmol/liter) level within 48 h of intravenous streptozotoci n injection. The untreated diabetic rats exhibited a reduction in body weight gain, with a 50% increase in daily food intake. In diabetic an imals treated with insulin for 4 weeks, the plasma glucose, body weigh t gain, and daily food intake were comparable to those of the non-diab etic controls. The plasma concentration of vitamin A was significantly reduced in the diabetic animals, whereas the hepatic content of vitam in A in them was significantly elevated. Treatment with implantable in sulin resulted in both plasma and liver concentrations of vitamin A re turning to the control non-diabetic levels. Dietary zinc supplementati on (120 mu g/g diet for 4 weeks) failed to improve the plasma concentr ation of vitamin A. These results suggest that the impaired metabolic availability of vitamin A in the presence of diabetes is caused by ins ulin deficiency.