Immunocytochemical evidence for a paracrine interaction between GIP and GLP-1-producing cells in canine small intestine.
Glucagon-like-peptide 1 (GLP-1) released from the intestine is considered to be an important incretin. We have recently demonstrated that glucose-dependent insulinotropic peptide (GIP) stimulated GLP-1 secretion from canine ileal L cells in culture. To investigate further the interplay between GLP-1- and GIP-secreting cells, we set out to determine the exact location and abundance of both cell types throughout the canine intestine. Canine small intestine was subdivided into 15-20 segments and investigated by immunocytochemistry with computer-assisted imaging. The abundance of GIP-, GLP-1- and somatostatin-immunoreactive cells was determined. GIP-secreting K cells were equally distributed in duodenum and jejunum, with the GLP-1-secreting L cells concentrated in the jejunum (5% duodenum, 73% jejunum and 22% ileum). These results indicated that the middle section of the small intestine containing 69% of the K cells also contained 51% of the L cells. Double immunostaining confirmed this overlap and furthermore over 30% of the L cells in this region were found adjacent to K cells. These results suggest the existence of a paracrine interaction between the K and L cells and indicate the importance of the jejunum in the regulation of insulin release by enteric-derived incretins.
Damholt
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AB
Diabetes Discovery, Novo Nordisk A/S, Bagsvaerd, Denmark.
Kofod
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H
Buchan
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AM
D000818:Animals; D029742:Caenorhabditis elegans Proteins; D004285:Dogs; D019858:Enteroendocrine Cells / Q000378:metabolism; D005260:Female; D005749:Gastric Inhibitory Polypeptide / Q000378:metabolism*; D007150:Immunohistochemistry; D007421:Intestine, Small / Q000166:cytology / Q000378:metabolism*; D007694:Killer Cells, Natural / Q000378:metabolism; D008297:Male; D008562:Membrane Glycoproteins / Q000378:metabolism*; D019899:Paracrine Communication; D051880:Receptors, Notch; D013004:Somatostatin / Q000378:metabolism; D019864:Somatostatin-Secreting Cells / Q000378:metabolism; D014018:Tissue Distribution
D029742:Caenorhabditis elegans Proteins; C060620:Glp-1 protein, C elegans; D008562:Membrane Glycoproteins; D051880:Receptors, Notch; D013004:Somatostatin; D005749:Gastric Inhibitory Polypeptide