Effects on GLP-1, PYY, and leptin by direct stimulation of terminal ileum and cecum in humans: implications for ileal transposition

Background: We do not have a unified, scientifically tested theory of causation for obesity and its co-morbidities, nor do we have explanations for the mechanics of the metabolic/bariatric surgery procedures. Integral to proffered hypotheses are the actions of the hormones glucagon-like peptide-1 (GLP-1), peptide YY (PYY), and leptin. The objective of this study was to obtain blood levels of GLP-1, PYY, and leptin after stimulation of the terminal ileum and cecum by a static infusion of a food hydrolysate in morbidly obese patients undergoing a duodenal switch procedure. Setting: University Hospital. Methods: Plasma levels of GLP-1, PYY, and leptin were obtained at 0, 30, 60, 90, and 120 minutes after instillation of 240 mL of a food hydrolysate into the ileum or cecum. Results: The mean +/- SD GLP-1 values by cecal stimulation for 0, 30, 60, 90, and 120 minutes were: 41.3 +/- 23.2; 39.6 +/- 21.8; 38.9 +/- 19.1; 47.4 +/- 22.3; 51.7 +/- 27.3 pM, and by ileal stimulation: 55.0 +/- 32.8; 83.4 +/- 16.1; 78.7 +/- 23.8; 84.7 +/- 23.5; 76.4 +/- 25.6. The mean +/- SD PYY values by cecal stimulation were: 62.1 +/- 24.8; 91.1 +/- 32.8; 102.1 +/- 39.6; 119.6 +/- 37.5; 130.3 +/- 36.7, and by ileal stimulation: 73.8 +/- 41.6; 138.1 +/- 17.7; 149.5 +/- 23.3; 165.7 +/- 24.3; 155.5 +/- 29.1. Percent change in PYY levels increased similar to 150%, GLP-1 increased similar to 50%, and leptin decreased similar to 20%. Conclusion: Direct stimulation of the human terminal ileum and cecum by a food hydrolysate elicits significant plasma GLP-1 and PYY elevations and leptin decreases, peaking at 90-120 minutes. The ileal GLP-1 and PYY responses exceed those of the cecum, and the PYY effect is about 3-fold that of GLP-1. The results of this study question the satiety premise for ileal transposition. (C) 2014 American Society for Metabolic and Bariatric Surgery. All rights reserved.