Electrophysiological evidence for distinct vagal pathways mediating CCK‐evoked motor effects in the proximal versus distal stomach

Non-technical summary Gut activity is controlled by the vagus nerves. In anaesthetized rats, both sensory and motor nerve activity evoked by intravenous injection of the gut hormone cholecystokinin were recorded in separate sub-branches of the gastric vagus nerve that supply the forestomach and hindstomach, respectively. Activity in the forestomach branch has not been studied before. Motor nerve activity in response to cholecystokinin differed between the two branches, in both timing and direction. Motor output to the forestomach paralleled sensory input from the hindstomach, while motor output to the hindstomach paralleled sensory input from the intestines. The data suggest that cholecystokinin released in the intestines after a meal immediately influences churning and propulsion of food by the hindstomach, via reflexes initiated by nearby intestinal sensory nerve terminals, but may influence gastric capacity only later, once circulating levels of cholecystokinin rise to levels capable of activating sensors in the hindstomach.