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Acta Physiologica 2011; Volume 202, Supplement 685
Scandinavian Physiological Society's Annual Meeting
8/12/2011-8/14/2011
Bergen, Norway
STIMULATION OF DUODENAL BICARBONATE SECRETION BY THE INCRETINS GLUCOSE-DEPENDENT INSULINOTROPIC PEPTIDE (GIP) AND GLUCAGON LIKE PEPTIDE-1 (GLP-1) BUT NOT THE RESPONSE TO PANCREATIC GLUCAGON IS PREVENTED BY OVERNIGHT FASTING
Abstract number: 6.4.1
FLEMSTROM1 G, MAKELA1 K, SJOBLOM1 M, ARDAHL1 A, JEDSTEDT1 G, HERZIG1 KH
1Physiology/Neuroscience, Uppsala University, BMC Box 593, SE-75124 Uppsala, Sweden; Email: [email protected]
Aims:
Overnight fasting abolishes the duodenal mucosal bicarbonate responses to appetite-re lated peptides like orexin-A and apelin-13 but not those to melatonin or VIP. Incretins are major regulators of insulin secretion and gastrointestinal motility. We have thus investigated effects of GIP and GLP-1 on the duodenal alkaline secretion in fed and fasted rats. Effects of glucagon like peptide-2 (GLP-2) and pancreatic glucagon were studied for comparison.
Methods:
Overnight fasted or continuously fed Lewis x Dark Agouti rats were anesthetized and mucosal bicarbonate secretion titrated in situ. Peptides were administered to the duodenum by close intra-arterial infusion. Total RNA was extracted from mucosal specimens and peptide receptor expressions measured by quantitative real-time PCR. Blood glucose was measured at the start and end of experiments.
Results:
GIP infused at rates of 60, 240 and 600 pmol kg-1 h-1 induced a dose-dependent rise (p< 0.01) in bicarbonate secretion, and fasting abolished this secretory response. GLP-1 caused a significant rise in the duodenal secretion but higher doses were required (p< 0.05 at 2400 pmol kg-1 h-1). As found with GIP, stimulation by GLP-1 occurred only in fed animals. Glucagon (600 pmol kg-1 h-1) induced secretory responses in fasted (p< 0.01) as well as fed (p< 0.05) animals. GLP-2 (600 pmol kg-1 h-1) did not affect the duodenal secretion. Fasting did not significantly affect GIP and GLP-1 but increased GLP-2 and glucagon receptor expressions. Glucagon, but not GIP or GLP-1, prevented the decline in blood glucose concentration observed in control animals.
Conclusion:
The incretins GIP and GLP-1 stimulate duodenal electrolyte secretion. Stimulation is feeding-dependent in spite of normal mucosal receptor expressions.
To cite this abstract, please use the following information:
Acta Physiologica 2011; Volume 202, Supplement 685 :6.4.1