Dietary fiber modulates intestinal proglucagon messenger ribonucleic acid and postprandial secretion of glucagon-like peptide-1 and insulin in rats.
Intestinal hormones stimulate more than 50% of the insulin response after oral glucose administration. Short chain fatty acids stimulate mucosal adaptation and may alter proglucagon messenger RNA and release of the insulin secretagogue, glucagon-like peptide-1 (GLP-1). Sprague-Dawley rats ingested a fiber-free elemetnal diet or an elemental diet supplemented with 30% fiber providing similar energy and nutrients for 14 days. The cecal and colonic short chain fatty acids contents were significantly higher in the 30% fiber group. Ileal proglucagon messenger RNA levels were significantly higher in the 30% group vs. the 0% group (11.47 +/- 0.87 vs. 6.52 +/- 0.87 densitometer units), respectively. Similar trends were seen in the colon (13.36 +/- 1.0 vs. 10.90 +/- 0.77 densitometer units; P = 0.07). Plasma GLP-1, insulin, and C peptide levels 30 min postoral glucose were significantly higher in the 30% fiber group vs. the 0% group (19.8 +/- 1.2 vs. 15.4 +/- 1.2 pg/ml, 2.67 +/- 0.4 vs. 1.29 +/- 0.5 ng/ml, and 964.4 +/- 94.4 vs. 530.2 +/- 120.4 pM, respectively). Plasma glucose and glucagon did not differ between groups. A diet supplemented with fiber is able to significantly alter proglucagon gene expression and modulate GLP-1 and insulin secretion. These novel findings deepen our understanding of the beneficial role of fiber in improving glucose homeostasis.
Reimer
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Department of Agricultural, Food, and Nutritional Science, University of Alberta, Edmonton, Canada.
McBurney
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D000818:Animals; D029742:Caenorhabditis elegans Proteins; D004043:Dietary Fiber / Q000008:administration & dosage / Q000494:pharmacology*; D004435:Eating / Q000502:physiology; D005232:Fatty Acids, Volatile / Q000032:analysis; D005260:Female; D005766:Gastrointestinal Contents / Q000737:chemistry; D005934:Glucagon / Q000235:genetics*; D007328:Insulin / Q000378:metabolism*; D000078790:Insulin Secretion; D007413:Intestinal Mucosa / Q000378:metabolism*; D008562:Membrane Glycoproteins / Q000378:metabolism*; D052336:Proglucagon; D011498:Protein Precursors / Q000235:genetics*; D012333:RNA, Messenger / Q000378:metabolism*; D011863:Radioimmunoassay; D051381:Rats; D017207:Rats, Sprague-Dawley; D051880:Receptors, Notch; D015430:Weight Gain / Q000187:drug effects
D029742:Caenorhabditis elegans Proteins; D004043:Dietary Fiber; D005232:Fatty Acids, Volatile; C060620:Glp-1 protein, C elegans; D007328:Insulin; D008562:Membrane Glycoproteins; D011498:Protein Precursors; D012333:RNA, Messenger; D051880:Receptors, Notch; D052336:Proglucagon; D005934:Glucagon