Neurohumoral control of the exocrine pancreas

Recent advances in the study of pancreatic exocrine secretion are reviewed, with an emphasis on neurohumoral mechanisms. In the past year, cDNA for the human pancreatic sodium-bicarbonate cotransporter was cloned, and the expressed protein was localized to pancreatic acini and ductal cells. Recent information suggests that the cholecystokinin B receptor has a role in pancreatic amylase release. Further evidence supports the concept of a protease-sensitive negative feedback mechanism regulating pancreatic exocrine secretion. Study of the expression of the receptors responsible for the regulation of pancreatic function has proven fruitful in the determination of the molecular mechanisms of hormone signal transduction and desensitization. Studies of peptide 1, pituitary adenylate cyclase-activating peptide, and gastrin-releasing peptide have shown how these peptides participate in the regulation of pancreatic secretion and have provided information on intracellular signaling pathways obtained using rat pancreatic tumor cells. Neural regulation via cholinergic receptors in isolated pancreatic acini and the mechanisms responsible for other neurotransmitters, such as calcitonin gene-related peptide, histamine, and dopamine, are reviewed. This review highlights recent discoveries in the neurohumoral regulation of pancreatic exocrine secretion.