Effects of Diabetes and Insulin on Hepatic Δ6 Desaturase Gene Expression

Abstract

It has been recognized that rat liver microsomal Δ6 desaturation activity is defective in experimental diabetes, a fact that may be reverted by means of insulin treatment. In the present study, we used streptozotocin-induced diabetic rats in order to determine the regulatory role of insulin on the expression of hepatic Δ6 desaturase gene. The abundance of hepatic Δ6 desaturase mRNA in the diabetic rats is sevenfold lower than in the control. Insulin administration to diabetic rats induces Δ6 desaturase mRNA eightfold within 24 h. The effect of insulin on the Δ6 desaturase mRNA was inhibited 70% with dibutyryl-cAMP and theophylline administration and 90% by cycloheximide administration. Therefore, our data demonstrate that the activity of hepatic Δ6 desaturase in response to insulin is, at least in part, regulated by pretranslational events that require the synthesis of an unknown protein(s).