Differential expression of A- and B-subtypes of cholecystokinin/gastrin receptors in the developing calf pancreas.

Cholecystokinin (CCK)/gastrin receptors were characterized in calf pancreatic plasma membranes from newborns, 28- and 119-day-old milk-fed preruminants, and 119-day-old weaned ruminants. Scatchard analysis of [125I]Bolton-Hunter reagent-[Thr28,Nle31]CCK-(25-33) binding indicated two classes of binding sites: high affinity sites exhibited significant higher affinity and binding capacity (P < 0.05) in 119-day-old ruminants than in 119-day-old preruminants (Kd = 0.13 +/- 0.02 vs. 0.35 +/- 0.08 nM; binding capacity (Bmax) = 53 +/- 12 vs. 18 +/- 5 fmol/mg protein). Pharmacological analysis using selective agonists and antagonists indicated the expression of the CCK-A receptor at birth, whereas the CCK-B receptor predominated at postnatal stages. At all stages, the binding was inhibited by guanosine 5'-[gamma-thio]triphosphate. Binding site identification by photoaffinity labeling showed that at birth, the labeling occurred mainly on a 78- to 96-kilodalton (kDa) component. In milk-fed animals, aged 28 and 119 days, two membrane-binding components were labeled at 78-96 and 43-52 kDa. In 119-day-old ruminants, labeling occurred mainly on a 40- to 47-kDa protein. Deglycosylation by endo-beta-N-acetylglucosaminidase-F of the 40- to 47- and 43- to 52-kDa components resulted in the formation of a 37-kDa membrane protein. Consequently, this study demonstrated 1) the differential expression of CCK-A and -B receptors in developing calf pancreas, 2) the predominance of CCK-B receptors in normal pancreas, and 3) the maturation of CCK-B receptors during the weaning period, which includes the glycosylation level. These results suggest that CCK may play a predominant role during the early postnatal development, while gastrin and CCK-B receptors can function progressively to regulate proliferation and exocrine secretion in the calf pancreas, especially from the weaning period.

Local and systemic immune responses to soybean protein ingestion in early-weaned pigs.

The development of local and systemic immune responses to soybean proteins was investigated in early-weaned pigs. Pigs were given either antigenic (ASP, n = 10 pigs) or non-antigenic (NASP, n = 8 pigs) soybean products (6 g of protein/d) from d 5 to 9 of age by stomach tube. After weaning at d 21, pigs were fed diets containing the corresponding soybean products and slaughtered between d 28 to 30. Diarrhea was 2.4-fold more frequent, the size of duodenal villi was reduced by 24 to 36%, and the eosinophil density in the duodenal mucosa was 13 times greater (P < .02) in the ASP pigs compared with the NASP pigs. A larger erythema area (P = .006) was observed in the ASP group than in the NASP group 30 min after an intradermal injection of glycinin, but no significant difference could be detected with alpha- or beta-conglycinin or whole soybean extracts. No difference in skin fold thickness was apparent between groups 24 h later. Intestinal, mesenteric lymph node, and blood lymphocytes did not proliferate when cultured with soybean proteins, regardless of dietary treatment. By ELISA, no difference between groups was observed in the circulating levels of total immunoglobulins (Ig) and IgM. Immunoblotting patterns of raw soybean with sera from 28-d-old pigs showed two bands (22 and 36 kDa) recognized by IgA and IgM, respectively, in the ASP group only. Finally, the adverse effects observed with antigenic soybean flour can be overcome by the use of alcohol-treated products.(ABSTRACT TRUNCATED AT 250 WORDS)

Response of the calf pancreas to differently processed soya bean and pea diets.

The purpose of this study was to determine the effect of replacing skim-milk powder by differently treated soya bean or pea products on growth, pancreas size and pancreatic enzyme activities in calves. Three separate experiments have been performed. In experiments 1 and 2, 28 and 21 male Holstein calves were divided into 4 or 3 groups, respectively, and fed either dairy products or milk substitutes in which protein was mainly provided by soya bean products differing in their protein concentration due to the technological processing applied. In experiment 3, 45 male Holstein calves were divided into 3 groups and were fed either dairy products, or raw or flaked pea flour as a protein source. After an experimental period of 99 +/- 4 days in experiments 1 and 2, and of 88 days in experiment 3, animal growth rate was significantly lower with raw pea flour (16%) and with the soya bean diet, which was highly concentrated in carbohydrates and allergenic proteins (13-27%). Pancreas weight decreased significantly (16-18%) with pea diets and tended to be lower (NS) with the water extracted, concentrated and heated flour (soya bean). Amylase-specific activity increased significantly (43%) with pea diets but showed opposite tendencies with the most refined soya bean products. Proteolytic enzyme activities were slightly influenced by dietary protein source, but this was not as obvious as in the literature reviewed. Specific messenger RNAs corresponding to amylase, trypsin and chymotrypsin seemed to increase (NS) with the soya bean diets, particularly with the less elaborated one. However, further investigations are required before any conclusions may be drawn concerning regulation levels of pancreatic adaptation to dietary protein. According to this study and the literature, results concerning pancreatic response to diets were different suggesting that the origin of soya bean, pea seeds and technological treatments applied to them were of great importance. Also, the level of incorporation into milk substitute and the presence of more or less antinutritional factors could influence pancreatic enzyme variations by complex mechanisms.

Gut regulatory peptide levels in bovine fetuses and their dams between the 3rd and 9th months of gestation.

Several gut regulatory peptides were measured by radioimmunoassay between 3 and 9 months of gestation in the plasma of 91 bovine fetuses and their dams, in fetal gastric content and in amniotic fluid. During gestation, plasma peptide concentrations did not change in cows. Likewise, fetal plasma concentrations of cholecystokinin, somatostatin, secretin and vasoactive intestinal polypeptide showed no variation while those of gastrin, pancreatic polypeptide and gastric inhibitory polypeptide increased during the last 6 months. Peptide levels in the fetus were higher than or equal to maternal concentrations. At 8-9 months of gestation, gastrin, CCK, secretin and somatostatin concentrations in amniotic fluid were lower than those measured in fetal gastric content and in maternal and fetal plasma. Therefore, a substantial endogenous endocrine production of regulatory peptides by the fetus probably exists as early as the third month of gestation, accompanied by a release into the lumen of the gut.

Kinetics of pancreatic exocrine secretion and plasma gut regulatory peptide release in response to feeding in preruminant and ruminant calves.

Pancreatic exocrine secretion and plasma cholecystokinin, gastrin, secretin, and somatostatin concentrations were examined in relation to feeding in 70- to 120-day-old preruminant and ruminant calves. The apparatus used was designed to immediately re-infuse the animal's own pancreatic juice and to carry out accurate measurements of the juice flow in real time and to take samples. In the preruminants, pancreatic juice, protein, and trypsin flows increased from 45 min before and until 15 min after the meal and decreased sharply thereafter over a period of 30 min. while protein and trypsin concentrations peaked after feeding. A significant increase in plasma gastrin and cholecystokinin (CCK), a fall in secretin and no change in somatostatin were observed after milk ingestion. By contrast, in the ruminants, feeding had no effect on the pancreatic secretion and on the plasma concentrations of these peptides. Similar and simultaneous patterns of juice flow and secretin, as well as of protein and trypsin concentrations, CCK and gastrin, could support the hypothesis that these gut regulatory peptides play a significant role in the regulation of the pancreatic function. In preruminant calves, the existence of cephalic, gastric and intestinal phases is discussed. In the ruminants, that of the ruminal phase is questionable.