Load-dependent effects of duodenal lipid on antropyloroduodenal motility, plasma CCK and PYY, and energy intake in healthy men

Abstract

Both load and duration of small intestinal lipid infusion affect antropyloroduodenal motility and CCK and peptide YY (PYY) release at loads comparable to and higher than the normal gastric emptying rate. We determined 1) the effects of intraduodenal lipid loads well below the mean rate of gastric emptying on, and 2) the relationships between antropyloroduodenal motility, CCK, 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 IL (Intralipid) infusions at: 0.25 (IL0.25), 1.5 (IL1.5), and 4 (IL4) kcal/min or 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, PW 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 of these effects were related to the lipid load (R > 0.5 or < -0.5, P < 0.05). Only IL4 reduced energy intake (in kcal: control, 1,289 +/- 62; IL0.25, 1,282 +/- 44; IL1.5, 1,235 +/- 71; and IL4, 1,139 +/- 65 compared with 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.

Effect of ileal fat perfusion on satiety and hormone release in healthy volunteers

“…With respect to the Effect of ileal fat infusion on satiety PWJ Maljaars et al duodenum, a relation between fat load and satiating effect has been demonstrated previously. 24 It is not apparent why no dose-dependent effects of ileal fat on satiety were observed. Several factors may be involved.…”

“…Recently, Pilichiewicz et al 24 demonstrated that, after duodenal infusion of lipid, a threshold infusion rate exists for fat to be able to induce PYY release. They demonstrated that a load of 0.25 kcal min À1 did not increase PYY plasma levels, whereas 1.5 kcal min À1 did.…”

“…They demonstrated that a load of 0.25 kcal min À1 did not increase PYY plasma levels, whereas 1.5 kcal min À1 did. 24 In our study with 3 g of fat, we infused 0.6 kcal min À1 through three infusion ports, each separated from the other by 15 cm, thus 0.2 kcal min À1 per infusion port. Although covering a larger area of the ileum, this infusion rate may result in a fat load that is below the sensing threshold to induce PYY release.…”

Effects of Intraduodenal Infusions of L-phenylalanine and L-glutamine on Antropyloroduodenal Motility and Plasma Cholecystokinin in Healthy Men

“…A comparison of the magnitude of the effects of L-Phe on APD motility and CCK secretion with the effects seen in response to ID protein, glucose, fat or free fatty acids in our previous studies with similar experimental designs reveals that the APD and CCK responses to L-Phe are rather small. 3,[37][38][39] However, it needs to be recognised that while free fatty acids were administered at comparable loads of 0.4 kcal/min, 39 protein, carbohydrate and fat were administered in much higher caloric loads of up to 4 kcal/min. 3,37,38 We have recently identified an important role of phasic pyloric pressures and plasma CCK as independent determinants of energy intake in response to ID lipid and carbohydrate infusions.…”

“…3,[37][38][39] However, it needs to be recognised that while free fatty acids were administered at comparable loads of 0.4 kcal/min, 39 protein, carbohydrate and fat were administered in much higher caloric loads of up to 4 kcal/min. 3,37,38 We have recently identified an important role of phasic pyloric pressures and plasma CCK as independent determinants of energy intake in response to ID lipid and carbohydrate infusions. 40 Although we do not relate the present data to effects on ad libitum eating, our findings contribute to a better understanding of the mechanisms underpinning the pronounced satiating capacity of high-protein diets.…”