Role of peptide tyrosine tyrosine (PYY) in the regulation of gastrointestinal motility and pancreatic exocrine secretion in sheep

• Published in: The Japanese Journal of Veterinary Research Vol. 49; no. 1; pp. 30 - 31
• Main Author: Takenori Onaga
• Format: Journal Article
• Language: English; Japanese
• Published: Graduate School of Veterinary Medicine Hokkaido University 31.05.2001
• ISSN: 0047-1917

The present study was performed to evaluate physiological roles of PYY in the regulatory mechanisms in the ovine alimentary tract. Immunohistochemistry revealed that PYY localized only in mucosal endocrine cells in the ileum and laicge intestine in sheep. In HPLC analysis, identical PYY-immunoreactivity with pure porcine PYY was detected from the mucosa of the ovine large intestine. Specific radioimmunoassay using scraped intestinal mucosa revealed that tissue contents of PYY in mucosa are higher in the colon and rectum in the ovine intestine whereas they are approximately ten-times smaller than that in the rat intestine. Plasma concentratien of PYY before feeding in sheep was as low as that in interdigestive period in rats and humans, however, it was hardly altered over 48 hours in sheep, even after feeding with lucerne pellets and hay or concentrate. Intravenous infusion of CCK, that has been shown to stimulate PYY release in nonruminant species, did not alter plasma concentration of PYY in sheep. No intraluminal infusions of oleic acid, butyric acid, casein, and maltose in the ileum and colon at supraphysiological concentrations increased plasma concentration of PYY. Moreover, no infusions of the four nutrients in the ileum exerted inhibitory effect on duodenal contractile activity in sheep. Finally, effects of PYY administration on the gastroduodenal motility and pancreatic exocrine secretion was examined in healthy mature sheep. Exocrine secretion of the ovine pancreas fluctuated in association with phases of spiking activity on a duodenal electromyogram and the exocrine secretion remained constantly at a high rate during phase II that took more than 80% of MMC.