THE ROLE OF ENDOGENOUS CHOLECYSTOKININ IN THE SENSORY TRANSDUCTION OFLUMINAL NUTRIENT SIGNALS IN THE RAT JEJUNUM

Some vagal afferent fibres are exquisitely sensitive to exogenous admi nistration of cholecystokinin (CCK) but their sensitivity to endogenou s CCK released by luminal stimuli has not been demonstrated directly, although implied from reflex and behavioural studies. We have therefor e utilised electrophysiological techniques to record afferent discharg e in mesenteric nerve bundles supplying the rat jejunum in response to luminal application of casein acid hydrolysate (CAH). CAH stimulated whole nerve afferent discharge in both in vivo and in vitro preparatio ns (P < 0.01) while single unit analysis revealed that fibres sensitiv e to CAH also responded to exogenous CCK. The responses to both CCK an d CAH were abolished by the CCKA antagonist devazepide. This study the refore supports the hypothesis that a functional relationship exists b etween CCK-containing enteroendocrine cells and the afferent fibres wh ose terminals lie within close proximity. (C) 1998 Elsevier Science ir eland Ltd. All rights reserved.