Activities of gastric, pancreatic, and intestinal brush-border membrane enzymes during postnatal development of dogs.

OBJECTIVE: To measure activities of digestive enzymes during postnatal development in dogs. SAMPLE POPULATION: Gastrointestinal tract tissues obtained from 110 Beagles ranging from neonatal to adult dogs. PROCEDURE: Pepsin and lipase activities were measured in gastric contents, and amylase, lipase, trypsin, and chymotrypsin activities were measured in small intestinal contents and pancreatic tissue. Activities of lactase, sucrase, 4 peptidases, and enteropeptidase were assayed in samples of mucosa obtained from 3 regions of the small intestine. RESULTS: Gastric pH was low at all ages. Pepsin was not detected until day 21, and activity increased between day 63 and adulthood. Activities of amylase and lipase in contents of the small intestine and pancreatic tissue were lower during suckling than after weaning. Activities of trypsin and chymotrypsin did not vary among ages for luminal contents, whereas activities associated with pancreatic tissue decreased between birth and adulthood for trypsin but increased for chymotrypsin. Lactase and gamma-glutamyltranspeptidase activities were highest at birth, whereas the activities of sucrase and the 4 peptidases increased after birth. Enteropeptidase was detected only in the proximal region of the small intestine at all ages. CONCLUSIONS AND CLINICAL RELEVANCE: Secretions in the gastrointestinal tract proximal to the duodenum, enzymes in milk, and other digestive mechanisms compensate for low luminal activities of pancreatic enzymes during the perinatal period. Postnatal changes in digestive secretions influence nutrient availability, concentrations of signaling molecules, and activity of antimicrobial compounds that inhibit pathogens. Matching sources of nutrients to digestive abilities will improve the health of dogs during development.

Dietary oligofructose and inulin protect mice from enteric and systemic pathogens and tumor inducers.

Prebiotics induce changes in the population and metabolic characteristics of the gastrointestinal bacteria, modulate enteric and systemic immune functions, and provide laboratory rodents with resistance to carcinogens that promote colorectal cancer. There is less known about protection from other challenges. Therefore, mice of the B6C3F1 strain were fed for 6 wk a control diet with 100 g/kg cellulose or one of two experimental diets with the cellulose replaced entirely by the nondigestible oligosaccharides (NDO) oligofructose and inulin. From each diet, 25 mice were challenged by a promoter of colorectal cancer (1,2-dimethylhydrazine), B16F10 tumor cells, the enteric pathogen Candida albicans (enterically), or were infected systemically with Listeria monocytogenes or Salmonella typhimurium. The incidences of aberrant crypt foci in the distal colon after exposure to dimethylhdrazine for mice fed inulin (53%) and oligofructose (54%) were lower than in control mice (76%; P < 0.05), but the fructans did not reduce the incidence of lung tumors after injection of the B16F10 tumor cells. Mice fed the diets with fructans had 50% lower densities of C. albicans in the small intestine (P < 0.05). A systemic infection with L. monocytogenes caused nearly 30% mortality among control mice, but none of the mice fed inulin died, with survival intermediate for mice fed oligofructose. Mortality was higher for the systemic infection of S. typhimurium (>80% for control mice), but fewer of the mice fed inulin died (60%; P < 0.05), with mice fed oligofructose again intermediate. The mechanistic basis for the increased resistance provided by dietary NDO was not elucidated, but the findings are consistent with enhanced immune functions in response to changes in the composition and metabolic characteristics of the bacteria resident in the gastrointestinal tract.

A non-terminal surgical procedure for chronic collection of exocrine pancreatic secretions from unrestrained dogs (Canis familiaris).

The ability of dogs to adaptively modulate secretion by the exocrine pancreas to match changes in the amounts and sources of macronutrients is poorly understood. We evaluated the use of re-entrant pancreatic catheters as a non-terminal, temporary approach for the chronic collection of exocrine pancreatic secretion using unrestrained dogs fed diets differing in composition. Re-entrant catheters were surgically placed in the accessory pancreatic duct of two adult mongrel dogs. Secretions were collected for 40 days, during which the dogs were fed three diets with different amounts and sources of macronutrients. The volume of secretion was recorded, protein content was measured, and the activities of trypsin, chymotrypsin, amylase, and lipase were assayed. Inter-dog variation was detected for the volume of secretion (ml/h) but not for protein content (mg/ml) or activities (U/ml) of the enzymes. The volume and composition of the secretion differed among diets. The responses were delayed about 4 days, were transient, and did not coincide with the changes in diet composition. We found that the re-entrant catheters were suitable for studying the exocrine pancreatic secretion of dogs. Our findings were inconclusive about the influence of diet but suggested that adult dogs have a limited and nonspecific response of pancreatic secretion.