A new twist in the brain-gut axis.
Gastrointestinal functions are precisely regulated by hormonal and neural negative feedback loops. In addition to the classic hormonal and vago-vagal reflex mechanisms, these studies indicate that there are direct actions of gut hormones on the dorsal vagal complex. The current data demonstrate that pancreatic polypeptide is released into the circulation by vagal-cholinergic dependent mechanisms. It travels to the brainstem in the circulation, transverses the blood-brain barrier through "leaky" regions of this barrier in the area postrema and nucleus of the tractus solitarius and binds to specific receptors in the dorsal vagal complex. By binding to these sites, pancreatic polypeptide can directly inhibit vagal input to the pancreas and other gastrointestinal organs. These observations provide an anatomic basis to explain why pancreatic polypeptide is a more potent inhibitor of the action of central stimulants of pancreatic secretion than it is of the response to peripheral secretagogues. They also establish a novel mechanism by which gut peptides can influence brain function directly.
Whitcomb
D C
DC
Department of Medicine, University of Pittsburgh, Pennsylvania.
Taylor
I L
IL
D000818:Animals; D001921:Brain / Q000502:physiology*; D004063:Digestion / Q000502:physiology*; D004068:Digestive System Physiological Phenomena; D006801:Humans; D008954:Models, Biological; D010179:Pancreas / Q000378:metabolism*