Long-term dietary lipid regimen alters adrenocortical function at the cellular level

Evidence indicates that dietary lipids influence adrenocortical function. In the present study, weanling rats were fed isocaloric synthetic diets for 6 and 12 months that contained 10% of one of the selected fatty acids as the predominant lipid: butter fat (high saturated, low polyunsaturated fat); olive oil (monounsaturated); corn oil (polyunsaturated); omega-3 ethyl ester mixture (long-chain polyunsaturates); elevated eicosapentaenoic acid; elevated docosahexaenoic acid. Adrenocortical cells derived from individual rats were evaluated for corticosterone and aldosterone responses to adrenocorticotropic hormone (ACTH). All comparisons were to the butter fat diet. Adrenocortical cell sensitivity to ACTH was not affected by the diets. However, there were differences in basal and maximal ACTH-induced corticosteroid production. Compared to the butter fat diet, the other diets variably decreased cellular corticosteroid production. Corticosterone and aldosterone production were affected similarly. The greatest decrease was most often seen with the omega-3 mixture diet (about -67%). At 6 months, the docosahexaenoic acid-elevated diet had selective suppressive actions on adrenocortical function whereas at 12 months, both docosahexaenoic and eicosahexaenoic acid-elevated diets had similar suppressive efficacies. The data indicate that a diet rich in high saturated, low polyunsaturated fat augments adrenocortical function and increasing the representation of long-chain unsaturated fatty acids suppresses adrenocortical function.