Influence of intraduodenally infused olive and coconut oil on postprandial exocrine pancreatic secretions of growing pigs.

The effect of dietary vegetable oils differing in fatty acid composition that were infused directly into the duodenum on exocrine pancreatic secretions in pigs has not previously been studied. The objective of the present study was to determine the acute response of the exocrine pancreas to vegetable oils with various fatty acid profiles under prandial conditions. Six growing pigs (BW 13.2 kg) were surgically prepared with pancreatic duct catheters and duodenal reentrant T-cannulas. The animals were fed twice a day (1000 and 1600) a commercial weaner diet at a rate of 2% of BW. Beginning with the morning feeding, olive oil, coconut oil, or saline as a control were infused in boluses every 5 min in total 0.1% of BW over a period of 1 h directly into the duodenum according to a 3 x 3 Latin square design. Pancreatic juice was collected over a period of 4 h, beginning 1 h preprandially (0900) until 3 h postprandially (1300). A time effect was observed after the infusion of olive oil on the volume of secretion, on protein contents and outputs, as well as on lipase contents and outputs and on colipase contents. The infusion of saline and coconut oil changed the runs of the curves for lipase and colipase outputs. No time x treatment interactions were observed regarding volume of secretion, protein contents and outputs, trypsin contents and outputs, and lipase outputs. The runs of the curves for lipase contents were different between the olive oil and saline treatment and between the olive oil and coconut oil treatment. The runs of the curves for the olive oil and saline treatment differed from each other regarding colipase contents. Pooled values of colipase outputs were elevated after coconut oil treatment, and a positive correlation between trypsin and colipase contents was found. Under prandial conditions, the exocrine pancreas responds differently in its acute secretion to different vegetable oils due to the differences in the fatty acid profiles.

Fats infused intraduodenally affect the postprandial secretion of the exocrine pancreas and the plasma concentration of cholecystokinin but not of peptide YY in growing pigs.

In pigs, the spontaneous secretion of the exocrine pancreas and the release of cholecystokinin (CCK) and peptide YY (PYY) after intraduodenal infusion of fully saturated synthetic fats differing in chain length was studied. Growing pigs (n = 6) were prepared with pancreatic duct catheters, duodenal T-cannulas and catheters placed in the jugular vein. The pigs were fed 2 g/100 g body twice daily. Beginning with the morning feeding, a medium-chain triglyceride (MCT: glycerol tricaprylate), a long-chain triglyceride (LCT: glycerol tristearate) or saline was infused at a rate of 0.1 g/100 g body. Pancreatic juice was collected, beginning 1 h preprandially until 3 h postprandially. Blood samples were obtained 15 min preprandially and 15, 45, 90 and 150 min postprandially. The infusion of MCT evoked a change in the trend of the curve for the volume of secretion of pancreatic juice, lipase and colipase concentrations and outputs. The trend of the curve did not change over time for CCK and PYY. Differences between the trends of the curves for the saline and MCT treatment were observed for volume of secretion, protein output, lipase content and output, trypsin and colipase output. Differences in the trends of the curves between MCT and LCT were obtained for the outputs of protein, lipase and colipase. Plasma CCK levels were lower as a result of the MCT treatment compared with the saline and LCT treatments. The results suggest an immediate, distinguished response of the porcine exocrine pancreas to fats differing in chain length.

Rat gastric procolipase: sequence, expression, and secretion during high-fat feeding.

BACKGROUND & AIMS: Procolipase, the cofactor for pancreatic lipase, was recently found in the rat stomach using immunohistochemistry. The aim of this study was to determine the sequence of rat gastric procolipase, to evaluate the expression and secretion during high-fat feeding, and to find out the conditions for activation of gastric procolipase to form colipase and enterostatin. METHODS: Gastric procolipase was cloned from a rat complimentary DNA (cDNA) library using a 32P-labeled pancreatic procolipase probe for screening. For the expression of gastric procolipase, rats were fed a high-fat diet for 0, 1, 2, 5, and 14 days. Gastric mucosa was collected for isolation of RNA and gastric juice for measurement of procolipase. After treatment with pepsin, HCl, and trypsin, gastric juice was analyzed on high-performance liquid chromatography for identification of enterostatin. RESULTS: The cDNA sequence for gastric procolipase was identical to that of pancreatic procolipase. High-fat diet decreased the expression of gastric procolipase. Enterostatin was present in the gastric juice, with pepsin and acid involved in the cleavage of gastric procolipase. CONCLUSIONS: Gastric procolipase is activated to release colipase and enterostatin. The role of gastric colipase may be to prepare lipase-catalyzed fat digestion already in the stomach. Gastric enterostatin may be involved in the onset of early satiety.

Carboxyl ester lipase (bile salt-stimulated lipase), colipase, lipase, and phospholipase A2 levels in pancreatic enzyme supplements.

BACKGROUND: Pancreatic lipolytic activity originates from lipase (LIP) and its cofactor colipase (COL), carboxyl ester lipase (CEL), and phospholipase A2 (PLA2). Yet there are few data on the levels of individual lipolytic enzymes in pancreatic enzyme supplements (PES). This study determines activity and immunoreactive mass in some commonly used PES and thus contributes to the understanding of the poor relationship between 'lipase dose' and clinical improvements. METHODS: Recommended doses of each PES were incubated at 37 degrees C for 2 h in a 1-mM Tris-maleate buffer, pH 7.0, containing 150 mM NaCl and 1 mM CaCl2. Aliquots for determinations of enzyme activities and for immunochemical mass were taken every half hour. For comparison a standard dose was defined as 10,000 declared lipase units. RESULTS: No simple parallelism between LIP, COL, CEL, and/or PLA2 activities was seen. The LIP contents ranged from 135% to 301% of the standard dose. None of the PES were short of COL (227%-504%). The variation in CEL was twentyfold, and in PLA2 sevenfold. Less variations were seen in the mass composition. There was considerable variation in activity to mass ratios (particularly for CEL), declared lipase units per recommended dose (6000-160,000), and cost (0.36-3.52 SEK). CONCLUSIONS: PES differ considerably in their content of lipolytic enzymes. CEL activities were relatively low and COL and PLA2 activities high compared with normal duodenal content. The manufacturing procedure can be improved to increase the lipolytic activity in PES in a broader meaning. It seems to be most important to increase the amount of CEL. From these in vitro data we advocate a more careful decision in the choice of PES for each patient, depending on the total clinical picture. Money can be saved without disadvantage to the patient.

Physicochemical characteristics of emulsions during fat digestion in human stomach and duodenum.

Seven fasting subjects were fitted with nasogastric and nasoduodenal tubes and received intragastrically a coarsely emulsified test meal. Gastric and duodenal aspirates were collected after 1, 2, 3, and 4 h. In the duodenum, most lipids (> 90%) were present as emulsified droplets 1-100 microns in size. Large droplets and unemulsified material present in the test meal (> 100 micron) disappeared, whereas smaller droplets (1-50 microns) were generated after 1 h of digestion. Thus the median lipid droplet diameter significantly decreased (19.6 vs. 56.5 microns in the test meal) and the droplet surface area significantly increased (1.58 vs. 0.70 micron2/g fat). Intermediate droplet diameters were 34.3, 46.3, and 27.6 microns after 2, 3, and 4 h, respectively. In the stomach, a comparable emulsion particle size pattern was observed, with median droplet diameters of 17.2, 37.9, 52.4, and 41.6 microns after 1, 2, 3, and 4 h, respectively. However, the extent of triglyceride hydrolysis was much lower in the stomach (6-16%) than in the duodenum (42-45%), where small droplets were enriched in lipolytic products, cholesterol, and phospholipids. The present findings show for the first time that most dietary lipids are present in the human duodenum as emulsified droplets 1-50 microns in size and that no further marked emulsification of dietary fat occurs in the duodenum compared with the stomach.

Procolipase is produced in the rat stomach--a novel source of enterostatin.

Procolipase was identified in the stomach by in situ hybridisation. A strong autoradiographic labelling of chief cells was seen in the fundus region, declining more distally and being almost absent in antrum. There was no labelling seen in the intestine. Colipase activity was estimated in rat gastric juice following pentagastrin stimulation and was found to average 2 microM. Furthermore, enterostatin, the N-terminal pentapeptide of procolipase, has been identified in the rat gut and pancreas. Extracts from gastric mucosa, intestinal mucosa and pancreas were purified by gel filtration (Sephadex G25), ion-exchange chromatography (CM-Sepharose) and HPLC (C18 reverse phase). Using an ELISA assay with antibodies directed against enterostatin, two forms of the peptide were identified both in the gut and in the pancreas, with the amino-acid sequences APGPR and VPGPR, respectively. APGPR was found to be the predominant form of enterostatin, whereas only a small amount had the structure VPGPR. Enterostatin in the form of APGPR, when injected intracerebroventricularly in female Sprague-Dawley rats, significantly reduced high-fat food intake in a two-choice situation of low-fat (14% fat by energy) and high-fat (38% fat) food. It is concluded that procolipase is produced in the stomach and secreted into the gastric juice. This is also a novel source of enterostatin.

Enterostatin in gut endocrine cells--immunocytochemical evidence.

The presence of enterostatin, a pentapeptide acting as a potential satiety signal in rats, was investigated in rat intestine by immunocytochemical methods. Using antibodies directed against the C-terminal part of enterostatin, the peptide was identified in endocrine cells in the antral part of the stomach and in the small intestine of rat. The immunoreactive cells were more frequent in the antrum and duodenum and became gradually fewer towards the distal small intestine. In some of the labeled endocrine cells, a coexistence of enterostatin with serotonin was revealed by immunocytochemical double staining, implying that the cells were enterochromaffin cells. In the pancreas, no enterostatin-immunoreactive cells were detected, indicating enterostatin to be included in its parent molecule, procolipase. In addition, the existence of procolipase in the gastrointestinal tract, including the pancreas, was investigated. Procolipase immunoreactivity was also identified, except in the pancreas, in chief cells in the fundus region of the stomach. The number of labeled cells declined distally in the stomach, finally being absent in the intestine. Immunoreactive enterostatin was measured with a specific ELISA method. Intestinal content and serum were found to average 540 +/- 70 and 50 +/- 4 nM, respectively. Pancreatic duct ligation strongly reduced the levels of enterostatin in intestinal content to 5.4 +/- 1.5 nM (p < 0.001), and also reduced the serum enterostatin level to 35 +/- 5 nM (p < 0.05). It is concluded that the peptide enterostatin in the rat is produced both in the exocrine pancreas, as part of pancreatic procolipase, and in gut endocrine cells, both sources of peptide being important for the circulating enterostatin.

Biology of enterostatin. II. Development of enzyme-linked immunosorbentassay (ELISA) for enterostatin (Val-Pro-Asp-Pro-Arg), the procolipase activation peptide.

Enterostatins belong to a family of pentapeptides (e.g., Val-Pro-Asp-Pro-Arg in pig, horse, dog, and rat; Ala-Pro-Gly-Pro-Arg in human and chicken; and Val-Pro-Gly-Pro-Arg in rat) derived from the amino-terminus of procolipase after the action of trypsin. Pharmacologic studies with Val-Pro-Asp-Pro-Arg have suggested a role for this peptide in appetite regulation and pancreatic insulin secretion. Studies into the distribution of enterostatins or the role of endogenous peptides have not been possible due to the lack of a suitable method for enterostatin assay. To this end, we raised a highly specific antibody and developed an enzyme-linked immunosorbent assay for Val-Pro-Asp-Pro-Arg. Using the newly developed assay we have shown the presence of Val-Pro-Asp-Pro-Arg-like immunoreactivity (2455 +/- 440 pmol/g) in the rat brain.

In vitro rat pancreatic digestive enzyme activities and raw and heated glandless cottonseed and soybean flours.

Higher nitrogen and lipid digestibilities have been obtained with diets containing cottonseed flour rather than soybean flour. To explain these results, in vitro studies were carried out to compare the effects of raw and heated glandless (without gossypol) cottonseed flours versus soybean flours on pancreatic digestive enzyme activities. These effects were compared with those obtained without addition of flour in standard assays. Apparent lipase (lipase colipase dependent) and potential lipase (lipase with saturating amounts of colipase), colipase, phospholipase A2, amylase, trypsin and chymotrypsin activities were measured on specific substrates. Phospholipase A2 and amylase activities were enhanced, while chymotrypsin activity was diminished with both raw and heated flours. Compared with raw and heated soybean flours, raw and heated cottonseed flours promoted higher potential lipase, chymotrypsin, trypsin and lipase activities. Heat treatment of cottonseed flour enhanced apparent lipase, colipase, chymotrypsin, trypsin activities and diminished potential lipase, phospholipase A2 and amylase activities. When soybean flour was heated, apparent lipase, phospholipase A2, chymotrypsin, trypsin and amylase activities were raised while those of potential lipase were decreased. Our findings show that in vitro raw or heated cottonseed flours affect less digestive enzymes than raw or heated soybean flours, apparent lipase activity excepted. Moreover, only chymotrypsin activities were seriously lowered with both flours, especially with raw soybean flour. Hypotheses are suggested to account for the differences in alterations.

Pathophysiology of the pancreatic defect in Johanson-Blizzard syndrome: a disorder of acinar development.

We compared pancreatic acinar and ductal secretion in two patients with Johanson-Blizzard syndrome, age-matched control subjects, and patients with other primary pancreatic diseases. Patients with Johanson-Blizzard syndrome had preservation of ductular output of fluid and electrolytes, as in patients with Shwachman syndrome but differing from those with cystic fibrosis, who have a primary ductular defect. They also had decreased acinar secretion of trypsin, colipase and total lipase, and low serum immunoreactive trypsinogen levels, consistent with a primary acinar cell defect.

Identification of enterostatin, the pancreatic procolipase activation peptide in the intestine of rat: effect of CCK-8 and high-fat feeding.

Enterostatin, the procolipase activation peptide, has been suggested in previous studies to act as a satiety signal for food intake, with a specificity for fat intake. In this study, by use of a competitive enzyme-linked immunosorbent assay with a detection limit of 4.115 nmol/L and within 6% intra- and interassay variation, the immunoreactive and chromatographic characterization of enterostatin in intestinal content was undertaken in Sprague-Dawley rats. Following intravenous infusion of cholecystokinin octapeptide (CCK-8; 200 pmol/kg/h) for 60 min, the concentration of intestinal enterostatin increased from a basal level of 2.0 +/- 0.7 microM to 5.64 +/- 1.1 microM at time point 60 min. The enterostatin level remained at 4.24 +/- 0.54 microM for 120 min after the CCK infusion had ceased. Pancreatic lipase and colipase activities in rat intestinal content also increased during the CCK-8 infusion. The enzyme activities reached the maximal level after 30 min of CCK infusion and thereafter progressively decreased to basal levels, remaining there during the following 2 h. The basal level of intestinal enterostatin in rats fed with standard pellets was found to be increased from 1.42 +/- 0.14 to 3.86 +/- 0.4, 3.17 +/- 0.54, and 5.02 +/- 1.6 microM on days 1, 3, and 7, respectively, after high-fat feeding. Parallel to the increase in intestinal enterostatin, there was a significant increase in pancreatic lipase and colipase activities in the intestine during the ingestion period of high-fat diet as compared with the control group. The estimated molecular mass of enterostatin immunoreactivity of intestinal content was similar to that of the synthetic pentapeptide. These results suggest that immunoreactive enterostatin (Val-Pro-Gly-Pro-Arg) is normally present in rat intestinal content, is significantly increased after stimulation with CCK-8, and is also increased after prolonged high-fat feeding.

The purification of ovine pancreatic lipase that is free of colipase using an improved delipidation method.

A modified procedure for the purification of ovine pancreatic lipase (triacylglycerol acyl-hydrolase, EC3.1.1.3) is described. The method is more rapid and more reproducible than that reported previously and results in a pure lipase preparation, that gives a better yield at the same specific activity, free of colipase and uncontaminated by lipid. The procedure involves the preparation of a lipid-free acetone powder from fresh pancreas without the use of chloroform or butanol as was used in the procedure described earlier. The aqueous purification of the lipase from the delipidated powder is similar to that described earlier, but includes the use of beta-mercaptoethanol and uses salt gradient elution from CM-Sepharose. An assay procedure for lipase is reported involving the extraction of released free fatty acids with chloroform/methanol before titrating with sodium hydroxide. A modification of this assay is used for the determination of colipase. The above assay procedure is compared to the potentiometric method reported previously. Polyacrylamide gel, amino acid composition analysis and N-terminal sequence data for the purified ovine lipase are presented.

Antigen specificity and cross-species reactivity of a monoclonal antibody (mAb 72.11) against porcine pancreatic procolipase.

We have studied the antigen specificity and cross-reactivity of a monoclonal antibody (mAb 72.11) of subclass IgG1, raised against the precursor form of porcine colipase (procolipase), whose epitope lies near the amino terminal region of the polypeptide. mAb 72.11 cross-reacts with native porcine, equine and human procolipase, as shown by immuno-inactivation and ELISA titration studies carried out on pure proteins, pancreatic tissue homogenate or pancreatic juice. The epitope site recognized by mAb 72.11 was further characterized by studying antibody binding to denatured procolipase. Reduced carboxymethylated procolipase reacted with mAb 72.11 in ELISA. Heat inactivated or reduced carboxymethylated porcine procolipase displaced antigen from the complex formed between antibody and native procolipase. The lack of sensitivity of epitope recognized by mAb 72.11 on procolipase to heat denaturation or reduction of the disulfide bridges is indicative that antigen specificity of mAb 72.11 is not dependent on the conformation of the antigenic site. Cross-reactivity of mAb 72.11 with procolipase from the three species demonstrates that substitution of amino acid at positions 1 and 3 causes no loss of antigenicity. Finally, mAb 72.11 was coupled to sepharose to isolate human procolipase from human pancreatic juice and to separate the precursor form from activated colipase non-adsorbed on the column.

Effect of insulin administration on contents, secretion, and synthesis of pancreatic lipase and colipase in rats.

After insulin administration in vivo, changes in pancreatic lipase, colipase and amylase contents and outputs were assayed and quantitatively compared. The incorporation of [35S]cysteine into individual enzymes was measured. The mRNA coding for lipase and amylase were determined by dot-blot hybridization. It was found that insulin dose-dependently decreased lipase and colipase contents, but only slightly decreased amylase content. Four hours after insulin administration (0.5 U/100 g), the contents of lipase and colipase decreased 80 and 72%, respectively, while amylase content decreased only about 25%. The decrease in amylase content was accompanied by a 21% increase in its output. The outputs of lipase and colipase only increased transiently and then sharply decreased to a level much lower than control. Total outputs of lipase and colipase could not quantitatively explain the great loss of lipase and colipase contents caused by insulin administration. After insulin injection, the incorporation of [35S]cysteine into amylase increased by 21%, whereas incorporation into lipase and colipase decreased by 18 and 25%, respectively. Dot-blot hybridization with cDNA probes revealed that lipase mRNA decreased by 50% 4 h after insulin administration, whereas mRNA for amylase did not significantly change. The results indicate an inhibitory effect of insulin administration on synthesis of pancreatic lipase and colipase, with the inhibition of lipase synthesis being at pretranslational level.

Development of enzyme-linked immunosorbent assay for free human pro-colipase activation peptide (APGPR).

Human pancreatic colipase is secreted as the inactive form procolipase. Activation involves tryptic cleavage of an N-terminal pentapeptide Ala-Pro-Gly-Pro-Arg (APGPR) which is known as procolipase activation peptide (CLAP). N-terminally haptenised synthetic APGPR was used to generate specific C-terminally directed anti-APGPR antibodies. The antiserum was used to develop a competitive enzyme linked immunosorbent assay (ELISA) specific for free CLAP with a detection limit of 12 nmol/l and an intra-assay coefficient of variation (CV) of 3.28% and an inter-assay CV of 5.82%. The release of immunoreactive CLAP from human pancreatic juice and chicken pancreas upon trypsinisation was demonstrated, as well as the absence of reactivity of the antisera with procolipase from which the CLAP is released. APGPR was found to be unstable in biological fluids. Immunoreactivity is rapidly lost with half life of 5 min and 4 h in human serum and urine respectively. This loss of reactivity can be significantly slowed by the addition of 20 mmol/l Zinc ions (Zn2+), while ethylenediaminetetra-acetic acid (EDTA) and other protease inhibitors were ineffective. In serum the moiety responsible for loss of immunoreactivity was found to have an estimated molecular mass of 200,000-300,000 Da. CLAP assay specifically reports procolipase activation and may help elucidate the mechanism of satiety as well as contribute to the recognition and understanding of the role of procolipase activation in diseases states such as pancreatitis.