Aldose Reductase and IGF-I Gene Expression in Aortic and Arteriolar Smooth Muscle during Hypo- and Hyperinsulinemic Diabetes

Abstract

Two genes whose expression is likely to be altered during diabetes mellitus are aldose reductase (AD) and insulin-like growth factor-I (IGF-I). We proposed that gene expression of AD is increased in vascular smooth muscle during diabetes mellitus due to hyperglycemia, while IGF-I expression is decreased in insulin-deficient diabetes and elevated in insulin-resistant diabetes. The mRNA for both was measured in the renal glomerulus, in the vascular smooth muscle of large arterioles from the brain, kidney, and small intestine, and in the aorta of hypoinsulinemic streptozotocin (STZ)-treated rats and hyperinsulinemic Zucker diabetic fatty (ZDF) rats. Quantitativein situhybridization was used to determine variations in expression. Expression of the AD gene was unchanged in STZ and ZDF rats, except for a decrease of about 50% in glomeruli and renal smooth muscle of STZ diabetic rats. Expression of IGF-I generally decreased in vascular smooth muscle of insulin-depleted STZ diabetic rats, but was normal in hyperinsulinemic ZDF rats. The data indicate that decreased expression of the AD gene is a specific problem in renal vascular smooth muscle and glomeruli in the insulin-depleted STZ model of diabetes. The expression of the IGF-I gene in vascular muscle was decreased in hypoinsulinemic diabetic animals, but did not increase in hyperinsulinemic diabetic rats.