Effects of insulin on the release of neuropeptide Y, [Met5]enkephalin and catecholamines from dog adrenal medulla

Abstract Insulin-induced hypoglycaemia is a well-known stimulating factor for the release of adrenaline from adrenal medulla. The present experiment investigates the co-release of catecholamines and neuropeptides (neuropeptide Y and [Met 5 ]enkephalin) from the adrenal medulla in chloralose-anaesthetized dogs after intravenous administration of insulin (0.3 U/kg). The increases in noradrenaline, adrenaline and [Met 5 ]enkephalin were 29.6-, 23.8-, and 27.9-fold basal values, respectively whereas the neuropeptide Y increase was only 1.6 times the baseline. These results show that adrenal [Met 5 ]enkephalin and catecholamines exhibit the same pattern of co-release which is not the case for adrenal neuropeptide Y.