Submitted on July 13, 2007
Accepted on October 8, 2007
Load-dependent effects of duodenal lipid on antropyloroduodenal motility, plasma CCK and PYY, and energy intake in healthy men
Amelia N Pilichiewicz1, Penny Papadopoulos1, Ixchel M Brennan1, Tanya J Little2, James H. Meyer3, Judith M. Wishart1, Michael Horowitz1, and Christine Feinle-Bisset1*
1 Medicine, University of Adelaide, Royal Adelaide Hospital, Adelaide, South Australia, Australia
2 Medicine, University of Adelaide, Royal Adelaide Hospital, Adelaide, South Australia, Australia; Adelaide, South Australia, Australia
3 Santa Monica, California, United States; Medicine, University of Adelaide, Royal Adelaide Hospital, Adelaide, South Australia, Australia
* To whom correspondence should be addressed. E-mail: christine.feinle{at}adelaide.edu.au.
Both the load and duration of small intestinal lipid infusion affect antropyloroduodenal motility and cholecystokinin (CCK) and peptide-YY (PYY) release at loads comparable to, and higher than, the "normal" gastric emptying rate. We determined the effects of intraduodenal lipid loads well below the mean rate of gastric emptying on (i) antropyloroduodenal motility, CCK and PYY, and appetite and energy intake, and (ii) the relationships with antropyloroduodenal motility, CCK and PYY, appetite and energy intake. Sixteen healthy males were studied on four occasions in double-blind, randomized fashion. Antropyloroduodenal motility, plasma CCK and PYY, and appetite perceptions were measured during 50-min intraduodenal lipid (Intralipid®) infusions at; (i) 0.25 ("IL0.25"), 1.5 ("IL1.5") and 4 ("IL4") kcal/min or, (iv) saline ("control"), after which energy intake at a buffet meal was quantified. IL0.25 stimulated isolated pyloric pressure waves (PWs) and CCK release, albeit transiently, and suppressed antral PWs, pressure wave sequences and hunger (P<0.05), but had no effect on basal pyloric pressure or PYY, when compared with control. Loads >1.5 kcal/min were required for the stimulation of basal pyloric pressures and PYY and suppression of duodenal PWs (P<0.05). All these effects were related to the lipid load (R>0.5 or <-0.5, P<0.05). Only IL4 reduced energy intake ([kcal], control: 1289±62, IL0.25: 1282±44, IL1.5: 1235±71, IL4: 1139±65*; *vs control and IL0.25, P<0.05). In conclusion, in healthy males the effects of intraduodenal lipid on antropyloroduodenal motility, plasma CCK and PYY, appetite and energy intake are load-dependent, and the threshold-loads required to elicit responses vary for these parameters.
