Neuroendocrinology of the pancreas; role of brain-gut axis in pancreatic secretion.

Exocrine pancreatic secretion, attributed initially to neural reflexes (nervism), was then found to depend also on enterohormones, especially secretin and cholecystokinin (CCK), released by the intestinal mucosa and believed to act via an endocrine pathway. Recently, CCK and other enterohormones were found to stimulate the pancreas by excitation of sensory nerves and by trigger of long vagovagal or ("brain-gut axis") enteropancreatic reflexes. Numerous neurotransmitters, such as acetylcholine, and certain neuropeptides, such as gastrin-releasing peptide (GRP), generated by neurons of the enteric nervous system (ENS) of the gut, have been implicated in the regulation of exocrine pancreas. Recently, peptides affecting appetite behavior and originating from the gut, such as leptin and ghrelin, or from the pancreas, such as pancreatic polypeptide and neuropeptide Y, appear to modulate the exocrine pancreas via hypothalamic centers. The aim of this review is to highlight the interaction of nerves and enterohormones in the regulation of exocrine pancreatic secretion.