Abstract
BackgroundMice, rats, and pigs are the three most used animal models when studying gastrointestinal peptide hormones; however their distribution from the duodenum to the distal colon has not been characterized systematically across mice, rats and pigs. We therefore performed a comparative distribution analysis of the tissue content of the major appetite- and glucose regulatory peptides: glucose-dependent insulinotropic polypeptide (GIP), glucagon-like peptide-1 (GLP-1), glucagon-like peptide-1 (GLP-2), oxyntomodulin/glicentin, neurotensin, and peptide YY (PYY) from the duodenum to distal colon in mice (n = 9), rats (n = 9) and pigs (n = 8), using validated radioimmunoassays.ResultsGLP-1, GLP-2 and oxyntomodulin/glicentin show similar patterns of distribution within the respective species, but for rats and pigs the highest levels were found in the distal small intestine, whereas for the mouse the highest level was found in the distal colon. In rats and pigs, neurotensin was predominantly detected in mid and lower part of the small intestine, while the mouse showed the highest levels in the distal small intestine. In contrast, the distribution of GIP was restricted to the proximal small intestine in all three species. Most surprisingly, in the pig PYY was found in large amounts in the proximal part of the small intestine whereas both rats and mice had undetectable levels until the distal small intestine.ConclusionsIn summary, the distribution patterns of extractable GIP, GLP-1, GLP-2, oxyntomodulin/glicentin, neurotensin are preserved across species whereas PYY distribution showed marked differences.Electronic supplementary materialThe online version of this article (doi:10.1186/s13104-016-1872-2) contains supplementary material, which is available to authorized users.
Highlights
Mice, rats, and pigs are the three most used animal models when studying gastrointestinal peptide hormones; their distribution from the duodenum to the distal colon has not been characterized systematically across mice, rats and pigs
GLP‐1, GLP‐2 and oxyntomodulin/glicentin Levels of amidated glucagonlike peptide-1 (GLP-1) increased significantly (Fig. 1a, P < 0.01) along the gastrointestinal tract in the mouse, whereas in the rat the highest levels were found in the distal ileum
Similar concentrations were found from distal ileum to distal colon, but nothing was detected in the duodenum or the proximal jejunum (Fig. 1a)
Summary
Rats, and pigs are the three most used animal models when studying gastrointestinal peptide hormones; their distribution from the duodenum to the distal colon has not been characterized systematically across mice, rats and pigs. We performed a comparative distribution analysis of the tissue content of the major appetite- and glucose regulatory peptides: glucose-dependent insulinotropic polypeptide (GIP), glucagonlike peptide-1 (GLP-1), glucagon-like peptide-1 (GLP-2), oxyntomodulin/glicentin, neurotensin, and peptide YY (PYY) from the duodenum to distal colon in mice (n = 9), rats (n = 9) and pigs (n = 8), using validated radioimmunoassays. The gastrointestinal tract plays a key role for the regulation of appetite and blood glucose [1,2,3] This is partly due to the secretion of the proglucagon (pcg) derived gut hormones: glucagon-like peptide 1 (GLP-1), glucagonlike peptide 2 (GLP-2), oxyntomodulin/glicentin; as well as non-pcg derived peptides: glucose-dependent insulinotropic peptide (GIP), neurotensin (NT), and peptide YY (PYY), all of which inhibit appetite [2], while some, in addition, potentiate glucose-stimulated insulin secretion (GIP and GLP-1) or suppress glucagon secretion (GLP1) [4]. With regards to the validity of mRNA data this depends on primer specificity and on post-transcriptional regulation such as the
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