title: Regulation of pancreatic exocrine secretion in goats: differential effects of short- and long-term duodenal phenylalanine treatment.
abstract: Four yearling goats (31.2 ± 2.5 kg), surgically fitted with common bile duct reentrant and duodenal catheter, were used in two 4 × 4 Latin square design experiments to investigate the effects of duodenal infusion of phenylalanine for different times on pancreatic exocrine secretion (PES). In experiment 1 (the long-term experiment), goats were duodenally infused with 0, 2, 4 or 8 g/day phenylalanine for 14 day. Pancreatic juice and jugular blood samples were collected over 1-h intervals for 6 h daily from day 11 to day 14 to encompass a 24-h day. In experiment 2 (the short-term experiment), goats were infused with phenylalanine for 10 h continuously at the same infusion rate as experiment 1 after feed deprivation for 24 h repeated every 10 day. Pancreatic juice and blood samples were collected at 0, 1, 2, 4, 6, 8 and 10 h of infusion. The volume and pH of pancreatic juice were measured, and a 5% subsample was composited and frozen until analysis of enzyme activities. Plasma was frozen until analysis of insulin and cholecystokinin (CCK). In experiment 1, pancreatic juice, α-amylase secretion and plasma CCK concentration responded quadratically (p < 0.05), with the top value observed at the 2 g/day phenylalanine. Trypsin secretion had a quadratic response (p < 0.05), with secretion increasing up to 4 g/day phenylalanine and decreasing thereafter. Phenylalanine linearly decreased pancreatic protein and lipase secretion (p < 0.05). The results of correlation analysis showed significant correlations (p < 0.05) between plasma CCK concentration and secretion of α-amylase and trypsin. However, the short-term phenylalanine infusion did not influence (p > 0.05) pancreatic juice, protein, α-amylase, lipase, trypsin secretion and plasma CCK concentration. These results indicate PES of ruminants is stimulated by phenylalanine and is potentially mediated by CCK in the long-term duodenal infusion treatment, but is not influenced by phenylalanine in the short-term duodenal infusion treatment.
authors.affiliation: College of Animal Science and Technology, Northwest A&F University, Shaanxi, Yangling, China.
authors.forename: Z P
authors.initials: ZP
authors.lastname: Yu
authors.forename: M
authors.initials: M
authors.lastname: Xu
authors.forename: J H
authors.initials: JH
authors.lastname: Yao
authors.forename: K
authors.initials: K
authors.lastname: Liu
authors.forename: F
authors.initials: F
authors.lastname: Li
authors.forename: Y
authors.initials: Y
authors.lastname: Liu
authors.forename: F
authors.initials: F
authors.lastname: Wang
authors.forename: F F
authors.initials: FF
authors.lastname: Sun
authors.forename: N N
authors.initials: NN
authors.lastname: Liu
mesh_terms: D000818:Animals; D004305:Dose-Response Relationship, Drug; D004333:Drug Administration Routes; D004334:Drug Administration Schedule; D004386:Duodenum; D006041:Goats / Q000502:physiology*; D010179:Pancreas / Q000187:drug effects*; D010649:Phenylalanine / Q000008:administration & dosage / Q000494:pharmacology*
chemical_list: D010649:Phenylalanine