Leucine markedly regulates pancreatic exocrine secretion in goats

Abstract

Four goats (30.1±1.3kg) with common bile duct re-entrant catheter and duodenal catheter were used to evaluate the effects of duodenal leucine infusion on pancreatic exocrine secretion and plasma parameters with two 4×4 Latin square design experiments. In the long-term infusion experiment, goats were fed twice daily [700g/day, dry matter (DM) basis] at 8:00 and 18:00hours and were duodenally infused with 0, 3, 6, 9g/day leucine for 14days. Pancreatic juice and jugular blood samples were collected over 1-h intervals for 6h daily from d 11 to 14days to encompass a 24-h day. In the short-term experiment, goats were infused leucine for 10h continuously at the same infusion rate with Experiment 1 after feed deprivation for 24h repeated every 10days. Pancreatic juice and blood samples were collected at 0, 1, 2, 4, 6, 8 and 10h of infusion. The results showed that the long-term leucine infusion did not affect pancreatic juice secretion, protein output, trypsin and lipase secretion and plasma insulin concentration, but linearly increased α-amylase secretion. No changes in pancreatic protein and lipase secretion were observed in the short-term infusion. Pancreatic juice and α-amylase secretion responded quadratically, with the greatest values observed in the 3 and 6g/day leucine respectively. Trypsin secretion linearly decreased, while plasma insulin concentration increased linearly with increased leucine infusion. The results demonstrated that duodenal leucine infusion dose and time dependently regulated pancreatic enzyme secretion not associated with the change in plasma insulin concentration.