vasoactive-intestinal-peptide and xenin-25

Xenin25 has a variety of physiological functions in the Gastrointestinal (GI) tract, including ion transport and motility. However, the motility responses in the colon induced by Xenin25 remain poorly understood. Therefore, the effect of Xenin25 on the spontaneous circular muscle contractions of the rat distal colon was investigated using organ bath chambers and immunohistochemistry. Xenin25 induced the inhibition followed by postinhibitory spontaneous contractions with a higher frequency in the rat distal colon. This inhibitory effect of Xenin25 was significantly suppressed by TTX but not by atropine. The inhibitory time (the duration of inhibition) caused by Xenin25 was shortened by the NTSR1 antagonist SR48692, the NK1R antagonist CP96345, the VPAC2 receptor antagonist PG99-465, the nitric oxide-sensitive guanylate-cyclase inhibitor ODQ, and the Ca

Topics: Animals; Colon; Enteric Nervous System; Gastrointestinal Agents; Gastrointestinal Motility; In Vitro Techniques; Male; Muscle Contraction; Muscle, Skeletal; Neural Inhibition; Neurotensin; Nitrergic Neurons; Rats, Sprague-Dawley; Receptors, Neurotensin; Substance P; Vasoactive Intestinal Peptide

Xenin is a 25 amino acid peptide detected in the gastric mucosa of various mammals. It has since been found in low concentrations in other tissues. Xenin plasma concentrations increase after meals. The present study reports some gastroenteropancreatic effects of this peptide in the dog. Intravenous infusion of 64 pmol/kg min synthetic xenin significantly inhibited pentagastrin-stimulated gastric acid secretion and stimulated exocrine pancreatic secretion of volume and protein. Further, intravenous infusion of xenin in a dose of 1.0 pmol/kg min stimulated jejunal motility in the anaesthetized dog. An intravenous infusion of 32 pmol/kg min xenin raised plasma concentrations of pancreatic polypeptide, vasoactive intestinal polypeptide, insulin and glucagon. The present experiments therefore indicate manifold bioactive properties of intravenously infused xenin in the dog, with jejunal motility the most sensitive target. Conclusions as to the physiological role of xenin cannot be drawn from the present experiments. The release of other hormonal peptides indicates a complex action of xenin.

Topics: Animals; Dogs; Female; Gastric Acid; Gastric Mucosa; Gastrointestinal Hormones; Gastrointestinal Motility; Glucagon; Infusions, Intravenous; Islets of Langerhans; Jejunum; Male; Muscle, Smooth; Neurotensin; Pancreas; Pancreatic Juice; Pancreatic Polypeptide; Pentagastrin; Peptides; Vasoactive Intestinal Peptide