Effect of neural blockades, gastrointestinal regulatory peptides, and diversion of gastroduodenal contents on periodic pancreatic secretion in the preruminant calf

Periodic fluctuations of gut regulatory peptides in phase with the duodenal migrating myoelectric complex in preruminant calves: effect of different sources of dietary protein

Four preruminant calves with implanted electrodes in the duodenum and a catheter in the external jugular vein were used for investigation of plasma gut regulatory peptide profiles during different phases of migrating myoelectric complex (MMC) in the small intestine. The effects of different dietary proteins on the rhythmic activity of gut peptides and gastrointestinal motility were compared. In particular, the effects of skimmed-milk protein (retaining physiological patterns of abomasal clotting, and abomaso-intestinal digesta flow) v. fish protein (devoid of clotting activity and modifying the digesta flow) were studied. In calves fed on the milk diet, plasma concentrations of pancreatic polypeptide, motilin, secretin, cholecystokinin (CCK) and somatostatin, but not vasoactive intestinal polypeptide or gastrin, fluctuated in phase with the duodenal MMC in the preprandial period. Feeding transiently affected the intestinal MMC and abolished the peptide fluctuations in a specimen-specific manner. In contrast, calves fed on the fish-protein diet showed more profound changes in intestinal MMC. In these animals the MMC-related fluctuations were significant only for plasma CCK. In conclusion, the source of dietary protein has an impact on the physiological endocrine function of the small intestine. Observed fluctuations of plasma gut regulatory peptides seem to be secondary to duodenal motility cycles.

Gut regulatory peptides in young cattle and sheep

This review summarizes recent advances on blood plasma patterns, receptors, secondary messengers and metabolism of gut regulatory peptides (i.e. gastrin, secretin, somatostatin, cholecystokinin, vasoactive intestinal polypeptide, pancreatic polypeptide, gastric inhibitory polypeptide, motilin), in young ruminants during fetal and perinatal stages, during the preruminant stage and at weaning. It also deals with their role in the digestive tract function and postabsorptive changes. Some pathological situations in young ruminants are considered. Recent molecular aspects of digestive enzyme synthesis are also reported.