Glucagon-like peptide 1 (GLP-1) is an appetite suppressing substance found in the brain and intestine. In the brain, GLP-1 acts as a satiety signal. In the intestine, it slows emptying of the stomach and stimulates the release of insulin from the pancreas.Pancreatic polypeptide is a 36-amino acid peptide secreted by islet cells of the pancreas in response to a meal and of unceain physiologic function;glucagon a polypeptide hormone secreted by the alpha cells of the islets of Langerhans in response to hypoglycemia or to stimulation by growth hormone. It increases blood glucose concentration by stimulating glycogenolysis in the liver and can be administered parenterally to relieve severe hypoglycemia from any cause, especially hyperinsulinism.Somatostatin is a cyclic tetradecapeptide hormone and neurotransmitter that inhibits the release of peptide hormones in many tissues. It is released by the hypothalamus to inhibit the release of growth hormone (GH, somatotropin) and thyroid stimulating hormone (TSH) from the anterior pituitary; it is also released by the delta cells of the islets of Langerhans in the pancreas to inhibit the release of glucagon and insulin and by the similar D cells in the gastrointestinal tract.Ref: Ganong&;s review of medical physiology;24th edition; page no-433