There is speculation that enteroglucagon and peptide YY are responsible for mediating the "ileal brake" known as a suppressive reaction of upper gastrointestinal motility and transit that is induced by the infusion of nutrients into the ileum. We studied changes in motility and transit in dogs with ileojejunal transposition in which the distal ileum is exposed to undigested nutrients. Nine adult mongrel dogs were equipped with strain gauge force transducers placed on the gastric body, antrum, duodenum, and proximal jejunum. Measurements of gastrointestinal motility, gastric emptying, and plasma levels of total glucagon-like immunoreactivity, immunoreactive glucagon, and peptide YY were obtained both before and after either ileojejunal transposition (5 dogs) or sham operation (4 dogs). Postprandial contractions in the gastric antrum and gastric emptying were significantly inhibited after ileojejunal transposition. The inhibitory effect of ileojejunal transposition on antral motor activity was found to correlate with the rise in plasma total glucagon-like immunoreactivity and peptide YY concentrations. However, plasma glucagon levels were unaffected by ileojejunal transposition. These results suggest that hypersecretion of enteroglucagon and peptide YY induced by ileojejunal transposition inhibits postprandial gastric motor function.
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