ABSTRACT
Gastrin is primarily produced by G cells of the gastric antrum. Lesser amounts are produced throughout the small and large intestine. Gastrin is also found in the pancreas, pituitary gland, hypothalamus, medulla oblongata, vagus and sciatic nerves. Its functions in the pituitary gland, brain and peripheral nerves are unknown. Gastrinsecreting tumors (gastrinomas) occur in the pancreas, and have been reported in primates, dogs, and cats. Gastrin excess leads to hyperchlorhydria (HCl excess), and secondarily to gastroduodenal ulceration and maldigestion (since pancreatic digestive enzymes do not reach their optimal pH, and are further denatured by the excess luminal HCl). Maldigestion leads to malabsorption, then to steatorrhea. Ulcerations of the stomach and/or duodenum lead to melena (Ch. 51).
