Altered retinol status and expression of retinol-related proteins in streptozotocin-induced type 1 diabetic model rats

Diabetes is a metabolic disorder characterized by chronic hyperglycemia. Advanced diabetes is associated with severe complications and impaired nutritional status. Here, we assessed the expression of retinol-associated proteins, including β-carotene 15,15'-monooxygenase (BCMO), lecithin:retinol acyltransferase (LRAT), aldehyde dehydrogenase (ALDH), and cytochrome P450 26A1 (CYP26A1), and measured retinol levels in the plasma and liver of streptozotocin (STZ)-induced type 1 diabetic model rats. Compared to the levels in the control rats, retinol levels in the plasma and liver of STZ rats were decreased and increased, respectively. Hepatic expression of the LRAT gene in STZ rats was lower than that in the controls. In the liver of STZ rats, the expression of ALDH1A1, a retinal metabolizing enzyme was higher, whereas ALDH1A2 expression was lower than in the controls. Hepatic CYP26A1 expression in STZ rats was significantly higher than in the control rats. BCMO expression levels in the liver and intestine of STZ rats were much lower than those of the controls. Altered BCMO expression might affect retinol status. It is considered that the metabolic availability of retinol was lessened despite the accelerated catabolism of retinol; therefore, retinol mobilization may be unbalanced in the liver of rats in the type 1 diabetic state.