Further characterisation of the 'ileal brake' reflex in man--effect of ileal infusion of partial digests of fat, protein, and starch on jejunal motility and release of neurotensin, enteroglucagon, and peptide YY.

Abstract

SUMMARY Previous studies have shown that ileal infusion of partially digested triglyceride inhibits jejunal motility. The partial digest used in those studies contained a mixture of glycerol, free fatty acid, mono-, di-, and triglycerides. In Part I of the present study we have separately infused emulsions containing either glycerol 3.1 g (n=6), oleic acid 9-6 g (n=6), triolein 10 g (n=12), or medium chain triglycerides 10 g (n=6) into the ileum and have recorded the effect this has on jejunal motility. Five further subjects received infusions of partial hydrolysates of corn starch 10 g and lactalbumin 7 g. Marked inhibition of jejunal pressure wave activity was seen after all three lipid infusions, per cent activity falling from a control of 37-7 (7.7) to 6-2 (2 1) and 22.4 (8.2)% 30 min after completing the oleic acid and triolein infusions respectively, and from a control value of 39.5 (4.1) to 17.7 (4.7) after MCTs (all p<005). No significant fall occurred after infusion of glycerol, protein or carbohydrate. All three lipid infusions raised plasma concentrations of neurotensin, enteroglucagon and peptide YY equally effectively, although only the rise in peptide YY correlated significantly with the inihibition ofjejunal pressure wave activity (r=0 80, n=6, p<OO5). In Part II of this study six subjects received a 3 ml/min jejunal infusion of an isotonic carbohydrate saline solution followed after three hours by a similar infusion of a partial digest of lipid. During each infusion flow and transit time was measured by marker and dye dilution. Jejunal infusion of the carbohydrate-saline solution was associated with low jejunal flow, 4.7 (1.0) ml/min and a mean transit time through the 50 cm study segment of 36.5 (7 1) min. By contrast jejunal infusion of partially digested triglyceride was associated with a markedly increased flow, 9.0 (1-2) ml/min, a fall in mean transit time to 20.3 (2.6) min and significant rises in pancreaticobiliary secretions. Jejunal triglyceride also increased the incidence of prolonged high amplitude jejunal pressure waves in four of six subjects. These studies suggest that there are important differences in the jejunal response to ileal versus jejunal lipid. While long and median chain free fatty acids infused into the ileum exert an inhibitory effect on jejunal motility, when infused directly into the jejunum partially digested triglyceride accelerates transit, increases jejunal flow and subtly alters the pattern of jejunal contractions.Patients with steatorrhoea caused by mucosal disease passing through the distal ileum and colon. This is have excessive quantities of partially digested fat associated with abnormally high postprandial con-

Peptide YY(3–36) Inhibits Morning, but Not Evening, Food Intake and Decreases Body Weight in Rhesus Macaques

“…These results are consistent with the proposed release of PYY in response to ingested fat (26,27). If PYY release is mediated by an enteral, nutrient-dependent mechanism (26,28,29), it is possible that the effects of PYY infusion on appetite and body weight may be greater in animals consuming a high-fat diet.…”

Mechanisms of gastric emptying disturbances in chronic and acute inflammation of the distal gastrointestinal tract

“…Other candidates include GLP-1 and PYY, which are mainly released from the distal ileum and colon and inhibit upper gastrointestinal functions including gastric emptying ("ileal brake") (26,27,31,32,48,55). Thus we hypothesized that delayed gastric emptying might be a consequence of disturbed release of CCK and/or PYY and/or GLP-1.…”

Gut chemosensing mechanisms

“…The ingestion of fat, which is subsequently hydrolyzed by lipases in the small intestine, is a strong stimulus of gut hormone secretion (58)(59)(60). Several GPCRs have been identified as sensors of the products of fat digestion ( Figure 2B).…”