The pancreas is an organ with both exocrine and endocrine functions. As an exocrine glandular organ, the pancreas produces and secretes digestive enzymes into the lumen of the duodenum. Cells with endocrine function form small islets distributed within the whole pancreas. They constitute 1 – 3 % of the pancreas mass. The pancreatic islets (islets of Langerhans) play their endocrine function through the secretion of hormones whose main roles are the control of glucose homeostasis (Martin and Crump 2003; Reusch et al. 2010). The islets consist of four types of cells which produce different hormones:
- α cells produce glucagon which causes an increase of gluconeogenesis and glycogenolysis, and decrease of glycogen synthesis;
- β cells produce insulin which acts in lowering the blood glucose concentration and contributes in glucose transport into most types of cells (exceptions: brain, liver, and red and white blood cells);
- δ cells produce somatostatin which plays a role in the inhibition of insulin, glucagon and pancreatic polypeptide secretion;
- F (or PP) cells produce pancreatic polypeptide which inhibits secretion of pancreatic digestive enzymes and contraction of the gallbladder.
Beside these hormones, other hormones (such as ACTH, TRH and others) have also been detected in the pancreatic islets, however their significance in the pancreas is unknown (Greco and Stabenfeldt 2007; Reusch et al. 2010).
Greco D.S., Stabenfeldt G.H. Endocrine Glands and Their Function. In: Cunningham J.G. and Klein B.G. (eds.) Textbook of Veterinary Physiology. 4 th ed. Saunders Elsevier, St. Louis, 2007, pp. 428-464.
Martin P.A., Crump M.H. The Endocrine Pancreas. In: Pineda M.H. and Dooley M.P. (eds.) McDonald’s Veterinary Endocrinology and Reproduction. 5 th ed. Blackwell Publishing, Ames, 2003, pp. 141-163.
Reusch C.E., Robben J.H., Kooistra H.S. Endocrine Pancreas. In: Rijnberk A. and Kooistra H.S. (eds.) Clinical Endocrinology of Dogs and Cats. An Illustrated Text. 2 nd ed. Schlütersche Verlagsgesellschaft, Hannover, 2010, pp. 155-185.