Effect of Pretreatment with Hydrocortisone on Insulin Secretory Response to Catecholamines in Isolated Islets from Rats Fed with a High Fat Diet

Summary

Islets isolated from rats fed with a high fat diet for 7 days were pretreated with hydrocortisone, and in the treated-islets the effect of glucose, epinephrine and dopamine on insulin secretion was examined. Glucose-stimulated insulin secretion in the untreated islets was not changed by the fat diet. Insulin secretion stimulated by hydrocortisone (10⁻⁶ M) in the presence of 2.8 mM glucose was twice higher in the control diet group than in the fat diet group. Pretreatment of the islets with hydrocortisone did not affect glucose-stimulated insulin secretion in the control diet group but remarkably reduced that in the fat diet group. Although the fat diet attenuated the inhibitory effect of catecholamines on insulin secretory response to glucose, pretreatment of the islets with hydrocortisone caused to restore the effect of catecholamines, especially at a low concentration. These results indicate that the combined action of a high fat diet and glucocorticoids may induce modification of α-adrenergic receptors in the B-cell.