PLASMA AND LIVER VITAMIN-A CONCENTRATIONS IN STREPTOZOTOCIN DIABETIC RATS

Decreased serum concentrations of vitamin A and retinol-binding protein have been previously identified in human subjects with type I diabetes mellitus. Here the effect of streptozotocin (STZ) induced diabetes in adult male rats on plasma and liver vitamin A concentrations was determined. The STZ injected rats displayed elevated plasma glucose levels, glucosuria and polyuria. Plasma vitamin A concentrations were significantly lower in the diabetic animals at 1, 3, and 6 weeks after the onset of diabetes than in the corresponding controls. The decrease in plasma vitamin A levels was lowest 1 week after STZ injection, higher after 3 weeks and highest after 6 weeks. In contrast, the liver vitamin A concentrations were significantly elevated in the diabetic groups at week 3 and 6 when compared with the controls. The increase in vitamin A concentration in the liver was directly related to the duration of the diabetic state. The fact that the plasma vitamin A levels were reduced in the diabetic animals despite the elevation in hepatic stores suggests an impairment in the mobilization of vitamin A from the liver into the blood stream. © 1990 Pergamon Press plc.