Glucagon-like Peptide 1 (7-36 hide) Secretion in Response to Luminal Sucrose from the Upper and Lower Gut: A Study Using α-Glucosidase Inhibition (Acarbose)

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Abstract
After nutrient ingestion there is an early response of glucagon-like peptide 1 (GLP-1) immunoreactivity, although GLP-1 is mainly produced in endocrine cells from the lower gut (ileum and colon/rectum), suggesting that indirect stimulation is important after the ingestion of carbohydrates that are predominantly absorbed from the upper intestine. To enable contact of sucrose with lower gut mucosa, sucrose was administered by mouth with and without the simultaneous ingestion of 100 mg of the alpha-glucosidase inhibitor acarbose to six normal healthy volunteers. There was an early increment in GLP-1 15 min after sucrose ingestion. With acarbose, sucrose reached the colon approximately 120 min after ingestion, as indicated by an increment in breath hydrogen exhalation (p < 0.0001), and GLP-1 release was prolonged (p < 0.0001). The sucrose-related increments in glucose, insulin, C-peptide, and gastric inhibitory polypeptide (GIP) and the suppression of glucagon were only marginally affected by acarbose administration. GLP-1 release appears to be influenced by indirect mechanisms (early response after sucrose) and by direct luminal contact with lower gut mucosal endocrine cells (late response with acarbose).