Insulinotropic and gastrin-releasing action of gastrin-releasing peptide (GRP).

The effect of intravenous administration of gastrin-releasing peptide ( GRP ) on serum gastrin and insulin levels was studied in ad libitum fed and 24-h fasted rats. Administration of GRP (55 micrograms/kg body weight) caused a significant (P less than 0.05) elevation in serum gastrin levels at 10, 30, 60, and 120 min in the rats fed ad libitum, whereas in the fasted rats, gastrin levels rose significantly only at 10 min. GRP did not cause insulin release in fasted rats, but in the fed rats, it led to a significant elevation in serum insulin levels at 10 and 30 min, in comparison to controls. GRP appears to have an insulinotropic action in addition to a gastrin-releasing effect.