Antropyloroduodenal, cholecystokinin and feeding responses to pulsatile and non-pulsatile intraduodenal lipid infusion

Abstract

The contribution of the pulsatile nature of gastric emptying to small intestinal feedback mechanisms modulating antropyloroduodenal motility and appetite is unknown. On separate days, eight healthy male volunteers (18-34 years) received randomized, single-blind, intraduodenal (ID) infusions of 10% Intralipid (2 kcal min(-1)), either continuously [CID], or in a pulsatile manner [PID] (5 s on/15 s off) and 0.9% saline (control) administered continuously, each at a rate of 1.8 mL min(-1) for 3 h. During each infusion, subjective ratings of appetite were assessed and antropyloroduodenal pressures recorded with a 16-lumen manometric assembly incorporating a pyloric sleeve sensor. Plasma cholecystokinin was measured from blood collected at regular intervals throughout the infusion. At the end of each infusion the manometric assembly was removed, subjects were offered a buffet meal and the energy and macronutrient content of the meal was measured. Both ID lipid infusions stimulated isolated pyloric pressure waves (IPPWs) (P < 0.001) and basal pyloric pressure (P < 0.01) and suppressed antral (P < 0.05) and duodenal (P < 0.05) pressure waves when compared to controls; there was no difference in the effects of CID and PID lipid on antropyloroduodenal pressures. Infusions of lipid significantly increased plasma CCK concentrations (P < 0.05) compared with saline, but concentrations were not different between the two modes of lipid delivery (P > 0.05, CID vs. PID). Both intraduodenal lipid infusions decreased hunger (P < 0.05), increased fullness (P < 0.05) and reduced energy intake (P < 0.05) when compared with controls; again there was no difference between CID and PID lipid. We conclude that at the infusion rate of similar 2 kcal min(-1), the acute effects of intraduodenal lipid on antropyloroduodenal pressures, plasma CCK concentration and appetite are not modified by a pulsatile mode of lipid delivery into the duodenum.