Effects of diabetes and insulin on hepatic Delta 6 desaturase gene expression

It has been recognized that rat liver microsomal Delta6 desaturation activi ty is defective in experimental diabetes, a fact that may be reverted by me ans of insulin treatment. In the present study, we used streptozotocin-indu ced diabetic rats in order to determine the regulatory role of insulin on t he expression of hepatic Delta6 desaturase gene. The abundance of hepatic D elta6 desaturase mRNA in the diabetic rats is sevenfold lower than in the c ontrol. Insulin administration to diabetic rats induces Delta6 desaturase m RNA eightfold within 24 h. The effect of insulin on the Delta6 desaturase m RNA was inhibited 70% with dibutyryl-cAMP and theophylline administration a nd 90% by cycloheximide administration. Therefore, our data demonstrate tha t the activity of hepatic Delta6 desaturase in response to insulin is, at l east in part, regulated by pretranslational events that require the synthes is of an unknown protein(s). (C) 2001 Academic Press.