Role of pancreatic polypeptide in the regulation of pancreatic exocrine secretion in dogs

Abstract

The effect of intravenous infusion of synthetic human pancreatic polypeptide (HPP) or a rabbit anti-PP serum on pancreatic exocrine secretion was studied in 10 dogs with gastric and Thomas duodenal cannulas. The infusion of HPP, at a dose of 1 microgram.kg-1.h-1, achieved a plasma PP concentration that mimicked the peak plasma concentration of PP in both interdigestive and postprandial states. This dose of HPP significantly inhibited pancreatic secretion in the interdigestive state. By contrast, immunoneutralization of circulating PP by a rabbit anti-PP serum resulted in significant increases (P less than 0.05) in both interdigestive and postprandial pancreatic secretion, including water, bicarbonate, and protein. The increase in the pancreatic secretion paralleled a decrease in circulating PP level, which lasted for as long as 5 days. Furthermore, the anti-PP serum blocked the inhibitory action of exogenous HPP on pancreatic exocrine secretion. The present study indicates that endogenous PP plays a significant role in the regulation of the pancreatic exocrine secretion in both interdigestive and digestive states. Thus we conclude that PP is another hormone regulating pancreatic exocrine secretion in dogs.

Regulation of Interdigestive Gastrointestinal Motility and Secretion

“…Since motilin stimulates and pancreatic polypeptide inhibits pancreatic secretion, their interaction may regulate interdigestive pancreatic secretion. Infusion of pancreatic peptide anti body into dogs increases interdigestive pancreatic secre tion which supports the hypothesis that pancreatic pep tide is a physiologic inhibitor [11], Similarly, somatoslatin-28 may be tonic inhibitor of human interdigestive pancreatic secretion: small increases of somatostatin-28 plasma levels decrease enzyme outputs without disrupting the coupling between secretion and motility [12], and systemic immunoneutralization of somatostatin-28 in creases enzyme outputs in rats [13], Although exogenous secretion and cholecystokinin affect interdigestive secre tion. they likely do not control the interdigestive period because their plasma concentrations do not change dur ing the interdigestive phases.…”

The islet-acinar axis of the pancreas: more than just insulin

“…Pancreatic polypeptide, irrespective of whether endogenously secreted or exogenously administered, is known to inhibit pancreatic exocrine secretion (87,108,173,197). Endogenous pancreatic polypeptide, which is released in a biphasic manner following ingestion of a meal, plays an inhibitory role on pancreatic exocrine secretion in both the interdigestive and postprandial states (173). The initial response to endogenous pancreatic polypeptide is believed to be mediated by the vagus (169,196).…”

Effects of pancreatic polypeptide on insulin action in exocrine secretion of isolated rat pancreas.

“…PP infused intravenously inhibits pancreatic exocrine secretion stimulated by secretin and/or cholecystokinin (CCK) in humans (Adrian, Besterman, Mallinson, Greenberg & Bloom, 1978;Greenberg, McCloy, Adrian, Chadwick, Baron & Bloom, 1978), dogs (Lin, Evans, Chance & Spray, 1977) and rats (Louie, Williams & Owyang, 1985). It also inhibits pancreatic exocrine secretion stimulated by food in dogs (Schwartz, 1983; Shiratori, Chen, Chang & Chey, 1986; Shiratori, Lee, Chang, Jo, Coy & Chey, 1988). Furthermore, infusion of PP antibody results in a marked increase in pancreatic exocrine secretion during the interdigestive and digestive period in dogs (Shiratori et al 1988).…”

“…It also inhibits pancreatic exocrine secretion stimulated by food in dogs (Schwartz, 1983; Shiratori, Chen, Chang & Chey, 1986; Shiratori, Lee, Chang, Jo, Coy & Chey, 1988). Furthermore, infusion of PP antibody results in a marked increase in pancreatic exocrine secretion during the interdigestive and digestive period in dogs (Shiratori et al 1988). It has been MS 1392 H. J.PARK, Y.L.…”