Synergistic stimulatory effect of glucagon‐like peptide‐1 (7–36) amide and glucose‐dependent insulin‐releasing polypeptide on the endocrine rat pancreas

Abstract

The interaction of glucagon‐like peptide‐1 (7–36)amide (GLP‐1) and glucose‐dependent insulin‐releasing polypeptide (GIP) on insulin release from the perfused rat pancreas was studied. The GLP‐ 1 stimulated (0.5 nmol/l), glucose‐induced (6.7 mmol/l) insulin secretory answer was enhanced by GIP (0.1, 1.0 and 10.0 nmol/l) to the arterial perfusate. This effect was maximal at 1 nmol/l GIP and smaller but still significant at 0.1 nmol/l GIP. The high GIP concentration of 10 nmol/l GIP did not further increase insulin secretion compared to the stimulation by 1 nmol/l GIP. Our data demonstrate an additive synergistic effect of GLP‐ 1 and GIP on the glucose‐induced insulin release. This supports the concept of an action ‘in concert’ of gastrointestinal incretin hormones postprandially released on the endocrine pancreas to guarantee adequate insulin answers after meals.