alpha-chymotrypsin and 4-diphenylacetoxy-1-1-dimethylpiperidinium

The aim of this study was to investigate the role of the parasympathetic (cholinergic and peptidergic) nervous system in the regulation of exocrine pancreas function in piglets during their early postnatal development. The cholinergic and peptidergic regulatory pathways of exocrine pancreatic function were tested by the specific muscarinic receptor blocker 4-diphenylacetoxy-N-methylpiperidine-methiodide (4-DAMP) and bombesin, respectively. At the age of 2 weeks, piglets were surgically fitted with a chronic pancreatic duct catheter, a duodenal re-entrant cannula and a jugular vein catheter. The experiments comprised a pre-weaning period, and a post-weaning period that commenced at the beginning of the 5th week of age. Intravenous infusion of 4-DAMP (100 pmol x kg(-1) x h(-1)) reduced the outflow of pancreatic juice, the output of total protein and the activity of trypsin, chymotrypsin, carboxyl ester hydrolase and amylase during preprandial and postprandial pancreatic secretion, in both the pre- and post-weaning periods. However, the inhibitory effect of 4-DAMP during postprandial secretion was significantly greater (P < 0.05) in suckling piglets. The infusion of bombesin (10, 100 and 1000 pmol x kg(-1) x h(-1)) stimulated exocrine pancreatic secretion in a dose-dependent manner during both the pre- and post-weaning periods. However, the stimulatory effect of 1000 pmol x kg(-1) x h(-1) bombesin on total protein output and the activities of trypsin, chymotrypsin and amylase were significantly higher (P < 0.05) in suckling piglets. In summary, our study showed that cholinergic and peptidergic mechanisms are involved in the regulation of exocrine pancreas function in piglets in both the pre- and post-weaning stages. 4-DAMP had a greater inhibitory effect on exocrine pancreatic secretion in piglets during the pre-weaning period. Thus, these observations suggest that the parasympathetic nervous system plays a dominant role in the functioning of the exocrine pancreas at this time. The action of bombesin suggests that it is a potent secretagogue for the exocrine pancreas in pigs during their postnatal development.

Topics: Amylases; Animals; Animals, Suckling; Bombesin; Carboxylesterase; Carboxylic Ester Hydrolases; Cholinergic Fibers; Chymotrypsin; Eating; Milk; Muscarinic Antagonists; Pancreas; Pancreatic Juice; Parasympathetic Fibers, Postganglionic; Piperidines; Postprandial Period; Swine; Trypsin; Weaning

Three Holstein steers (345 +/- 22 kg) surgically fitted with a pancreatic cannula were used in two 3 x 3 Latin square design experiments to examine the effects of slaframine (SF), a muscarinic agonist, or 4-diphenylacetoxy-N-methylpiperidine methiodide (4DAMP), an M3 muscarinic glandular receptor antagonist, on pancreatic exocrine secretion. Pancreatic exocrine secretion was collected for 8 h postdosing at 30-min intervals beginning 1 h postfeeding. In experiment 1, steers were dosed with 0, 25, or 50 micrograms.kg-1 body weight (BW) of SF. Secretion of pancreatic juice and the pH of the secreted juice increased linearly (p < 0.05) with SF; however, secretion rate showed a time by treatment interaction (p < 0.05), as treatments converged 7 h postdosing. Trypsin secretion tended (p < 0.10) to show a quadratic response to SF administration, with the 25 micrograms SF.kg-1 BW dose having the lowest value. In experiment 2, steers received 50 micrograms.kg-1 BW of SF (positive control), 113 micrograms.kg-1 BW of 4DAMP (isosmolar with SF), or both. SF caused a greater pancreatic fluid secretion (p < 0.10) than 4DAMP, with SF plus 4DAMP intermediate. A time by treatment interaction (p < 0.04) was found, since treatments converged 8 h postdosing. Trypsin secretion was higher (p < 0.05) for SF than the other treatments. Chymotrypsin, alpha-amylase, and protein secretion were not affected. SF and 4DAMP alter pancreatic fluid secretion in the steer but have minimal effects on enzyme secretions.

Topics: Alkaloids; alpha-Amylases; Animals; Cattle; Chymotrypsin; Hydrogen-Ion Concentration; Male; Muscarinic Antagonists; Pancreas; Pancreatic Juice; Parasympatholytics; Parasympathomimetics; Piperidines; Proteins