Influence of methionine-enkephalin analogue (FK-33-824) on the secretion of pancreatic hormones.

To determine the effects of methionine-enkephalin on secretion of pancreatic hormones, five healthy male adults were intramuscularly given 0.5 mg of FK 33-824, a methionine-enkephalin analog and blood levels of pancreatic hormones were measured at different time intervals. FK 33-824 significantly lowered basal levels of plasma insulin (IRI) and pancreatic polypeptide and decreased IRI secretion in 75 g-OGTT. It also delayed the elevation of blood sugar level in 75 g-OGTT. No change occurred in the basal levels of plasma glucagon, somatostatin and blood sugar. These results imply that methionine-enkephalin in the pancreas and alimentary tract may act as an inhibitor on the secretion of insulin and pancreatic polypeptide and hence relates to the absorption of sugar.