Action of secretin on pancreatic enzyme secretion in man. Studies on pure pancreatic juice

Post-surgical exocrine pancreatic insufficiency

Being an underdiagnosed and under or insufficiently treated condition, surgical pancreatic exocrine insufficiency (PSP) is the condition in which pancreatic enzymes are insufficient for digestion because of gastrointestinal (GI) surgery involving the upper GI tract, biliary ducts, or the pancreas, and and leading to potential malnutrition and deterioration in quality of life. Age, obesity, history of tobacco use, family history of diabetes, surgery due to a malignant tumor, presence of steatorrhea, jaundice, weight loss, and intraoperative findings of hard pancreatic texture have been associated with a higher risk of PSP. Pancreatoduodectomy (PD) has demonstrated an increased risk of developing PSP, with a prevalence between 19-100%. Distal pancreatectomy (DP) and central pancreatectomy (CenP) are associated with less risk of PSP, with a prevalence of 0-82% and 3.66-8.7%, respectively. In patients with chronic pancreatitis (CP), PSP was associated with 80% in Partington-Rochelle procedure, 86% in Frey procedure, 80% in duodenum preserving pancreatic head procedure, >60% in PD and 27.5-63% in DP. Fecal elastase-1 (FE-1) is a generally accepted tool for diagnosis. Treatment is recommended to start as soon as a diagnosis is achieved, or clinical suspicion is high. Pancreatic enzyme replacement therapy improves symptoms of malabsorption, facilitates weight gain, and ultimately improves patients' quality of life. Starting dosage is between 10,000-50,000 units in snacks and 50,000-75,000 units in main meals, administered throughout food intake, though further data specifically on PSP are needed. Follow-up in PSP is recommended on an on-demand basis, where malnutrition should be assessed.

The roles of calcium and ATP in the physiology and pathology of the exocrine pancreas

This review deals with the roles of calcium ions and ATP in the control of the normal functions of the different cell types in the exocrine pancreas as well as the roles of these molecules in the pathophysiology of acute pancreatitis. Repetitive rises in the local cytosolic calcium ion concentration in the apical part of the acinar cells not only activate exocytosis but also, via an increase in the intramitochondrial calcium ion concentration, stimulate the ATP formation that is needed to fuel the energy-requiring secretion process. However, intracellular calcium overload, resulting in a global sustained elevation of the cytosolic calcium ion concentration, has the opposite effect of decreasing mitochondrial ATP production, and this initiates processes that lead to necrosis. In the last few years it has become possible to image calcium signaling events simultaneously in acinar, stellate, and immune cells in intact lobules of the exocrine pancreas. This has disclosed processes by which these cells interact with each other, particularly in relation to the initiation and development of acute pancreatitis. By unraveling the molecular mechanisms underlying this disease, several promising therapeutic intervention sites have been identified. This provides hope that we may soon be able to effectively treat this often fatal disease.

Pancreatic Exocrine Insufficiency as a Complication of Gastrointestinal Surgery and the Impact of Pancreatic Enzyme Replacement Therapy

BACKGROUND

Pancreatic exocrine insufficiency (PEI) is characterized by inadequate production, insufficient secretion, and/or inactivation of pancreatic enzymes, resulting in maldigestion. The aim of this review was to analyze the prevalence and pathophysiology of PEI resulting from gastrointestinal (GI) surgery and to examine the use of pancreatic enzyme replacement therapy (PERT) for effectively managing PEI.

SUMMARY

A targeted PubMed search was conducted for studies examining the prevalence and pathophysiology of PEI in patients following GI surgery and for studies assessing the effects of PERT in these patients. PEI is a common complication following GI surgery that can lead to nutritional deficiencies, which may contribute to morbidity and mortality in patients. Timely treatment of PEI with PERT can prevent malnutrition, increase quality of life, and possibly reduce the associated mortality. Treatment of PEI should aim not only to alleviate symptoms but also to achieve significant improvements in nutritional parameters. Dose optimization of PERT is required for effective management of PEI, in addition to regular assessment of nutritional status, appropriate patient education, and reassessment if symptoms return. Key Messages: Difficulties in detecting PEI following GI surgery can result in undiagnosed and untreated maldigestion, leading to metabolic complications and increased morbidity. Both are preventable by early administration and monitoring for optimal doses of PERT.

Role of the gut in modulating lipoprotein metabolism

The intestinal production of lipoproteins is one of the key processes by which the body prepares dietary lipid for dissemination to locations throughout the body where they are required. Paramount to this is the relationship between dietary lipid and the enterocytes that line the gut, along with the processes which prepare this lipid for efficient uptake by these cells. These include those which occur in the mouth and stomach along with those which occur within the intestinal lumen itself. Additionally, the interplay between digested lipid, dual avenues for lipid uptake by enterocytes (passive and lipid transporter proteins), a system of intercellular lipid resynthesis and transport, and a complex system of lipoprotein synthesis yield a system open to significant modulation. In this review, we will attempt to outline the processes of lipid digestion, lipoprotein synthesis and the exogenous and endogenous factors which exert their influence.

Value of pancreatic antibiotic concentration in treatment of secondary infection of serve acute pancreatitis

Secondary pancreatic infection represents the most serious complication with fatal outcome in severe acute pancreatitis (SAP). Preventing and curing secondary infection of pancreas is the key obstacle to minimize the mortality of these patients. The studies on blood-pancreatic juice barrier as well as penetration and pancreatic tissue concentration of antibiotics have improved the antibiotic prophylaxis or treatment of pancreatic infection. In the future, potential therapeutics that can enhance the antibiotic concentration and efficacy may help to prevent and treat the secondary infection of SAP.

Biliary atresia due to delayed maturation of the gut hormones' system?--Introducing a new treatment modality

BACKGROUND

Congenital biliary atresia is suspected to originate from prenatal biliary duct inflammation of unknown etiology.

OBJECTIVE

Based on clinical grounds, we aimed to establish a hypothesis on the primary cause of inflammation, and to suggest a causal treatment modality.

CASE REPORT

History. A 28 years old Turkish woman had lost her first child aged two years from congenital biliary atresia (parents second degree cousins). After a miscarriage, in her otherwise uneventful third pregnancy sonography at 34 wks revealed echogenic material in the fetal gallbladder. Nine days later the gallbladder was completely filled with sludge. Chemical inflammation was suspected, and birth was induced at 36+3 weeks in order to allow for surgical flushing of the bile duct. Neonatal clinical chemistry was insuspicious. There was no spontaneous resolution of the sludge within the first 24 hours of life. A trial of medical treatment with intermittent i.v. secretin (0.03 CU/kg/h) and i.v. coeruletid (60 ng/kg/h) was started. Within 24 hours, sludge had resolved.

CONCLUSIONS

We hypothesize that dysmaturation may lead to insufficient induction/production/activity of intrinsic gut hormones resulting in prenatally impaired bile flow, or even inspissated bile. Familial occurrence suggests a genetic defect. Exogenous hormone therapy might be an appropriate treatment modality.

Effect of secretin on serum pancreatic enzymes and on the Wirsung duct in chronic nonpathological pancreatic hyperenzymemia

AIM

Chronic nonpathological pancreatic hyperenzymemia (CNPH) is a new syndrome characterized by an increase in serum pancreatic enzymes in the absence of pancreatic disease. The aim of this study was to increase our understanding of this condition by determining the serum pancreatic enzyme response as well as changes in the caliber of the Wirsung duct after secretin stimulation.

METHODS

Twenty subjects with CNPH and 9 healthy subjects without CNPH were studied. Blood samples were drawn 5 and 0 min before and 5, 10, 15, 30, 45, and 60 min after intravenous injection of secretin (1 U/kg). Amylase, pancreatic isoamylase, and lipase concentrations were determined. The caliber of the Wirsung duct was measured by ultrasonography.

RESULTS

The injection of secretin caused a marked and statistically significant (p < 0.05) increase in serum pancreatic enzymes in the subjects with CNPH that persisted for the duration of the study. The increase over the basal value was in the range of 1.2- to 1.6-fold for amylase, 1.4- to 2.1-fold for pancreatic isoamylase, and 2.6- to 4.2-fold for lipase. In the control subjects the increase was mild, but statistically significant (p < 0.05), ranging from 1.1- to 1.2-fold for amylase, 1.2- to 1.4-fold for pancreatic isoamylase, and 1.5- to 2.2-fold for lipase. The injection of secretin caused a slight increase in the diameter of the Wirsung duct in both groups of subjects, but this was statistically significant only during the first 30 min of the study.

CONCLUSIONS

The serum pancreatic enzyme response to secretin was more marked in CNPH than in controls. The Wirsung duct showed no alterations after secretin injection that would help to explain the hyperenzymemia.

Impaired pancreatic secretion in severely malnourished patients is a consequence of primary pancreatic dysfunction

Severe undernutrition has been associated with reduced secretions of gastric acid and pancreatic enzymes. This may be the result of an impaired gut mucosal response to food and primary gastric parietal and pancreatic acinar cell secretory dysfunction as a consequence of the poor nutritional state. To investigate the relative contributions of these factors, severely undernourished patients underwent enteral-meal-stimulated (ES; n = 7) or intravenous hormone (pentagastrin and cholecystokinin-8)-stimulated (HS; n = 12) gastric acid and pancreatic enzyme secretion before and after a period of nutritional support. Results were evaluated in comparison with normal healthy control subjects (ES = 7, HS = 10). In the control subjects, enteral-meal and cholecystokinin-8 stimulation resulted in similar outputs of the pancreatic enzymes amylase (2213 versus 2305 U/h), lipase (84.93 versus 118.6 U/h), and trypsin (498.9 versus 341.4 U/h), whereas acid output was significantly lower in the ES group (10.90 versus 25.53 mEq/h; P < 0.01). Compared with controls, malnourished groups had significantly reduced secretions of amylase (ES = 870.1 U/h, HS = 686.5 U/h; P < 0.02), lipase (ES = 30.68 U/h, HS = 25.96 U/h; P < 0.02), and trypsin (ES = 175.6 U/h, HS = 109.3 U/h; P < 0.01). The response to enteral-meal or CCK-8 stimulation was comparable. Gastric acid was similarly reduced in the undernourished patients (ES = 4.39 mEq/h, HS = 5.04 mEq/h; P < 0.01). After refeeding, secretion of amylase (ES = 2351 U/h, HS = 2228 U/h) and lipase (ES = 58.83 U/h, HS = 84.91 U/h) improved to levels not significantly different from controls, whereas trypsin (ES = 226.4 U/h, HS = 213.1 U/h; P < 0.03) and acid secretion (ES = 3.52 mEq/h, HS = 11.85 mEq/h; P < 0.01) remained significantly impaired. Severe undernutrition was associated with primary gastric parietal and pancreatic acinar cell dysfunction, which, at least in the case of pancreatic enzymes, appeared to be the determining factor controlling secretion in these patients.

Adaptation of the human pancreas to inhibition of luminal proteolytic activity

BACKGROUND & AIMS

Feedback regulation of pancreatic enzyme secretion is well established in animals, and their pancreases are able to adapt to intraduodenal inhibition of pancreatic enzymes by proteinase inhibitors such as Camostate (FOY-305; Schwarz GmbH, Monheim, Germany). In this study, we addressed whether similar adaptive changes occur in the human pancreas after 4 weeks of 2 g/day Camostate application.

METHODS

Before, at the end of, and 2 weeks after 4-week Camostate treatment (four times 500 mg daily), pancreatic changes were analyzed with the use of a secretin-cerulein test, a test-meal stimulation, cholecystokinin plasma measurement, and standardized ultrasonographic investigations of the pancreas.

RESULTS

Duodenal trypsin output after secretion stimulation was significantly increased (+44%; P < 0.01) and duodenal bicarbonate output decreased 22% (P < 0.05) after 4 weeks of Camostate application. The size of the pancreatic head (vertical) increased 8% (P < 0.05) at week 4 and decreased to pretreatment values 2 weeks after treatment (week 6). The other three diameters measured (head oblique, body, and tail) showed a similar pattern. Stimulated cholecystokinin plasma levels 15 minutes after application of a standard test meal increased 62% (P < 0.05).

CONCLUSIONS

The human pancreas adapts to oral application of the proteinase inhibitor Camostate. These findings support the theory that feedback control of the exocrine pancreas operates in humans.

Role of vasoactive intestinal polypeptide (VIP), secretin and gastrin in the genesis of the late exocrine pancreatic hypersecretion, food intake dependent in conscious dogs

Plasma levels of vasoactive intestinal polypeptide (VIP), secretin and gastrin were studied in four saphenous vein-catheterized dogs during the first 12 h after ingestion of a standard solid meal. Under these conditions we found significant postprandial increases in secretion only, which rose from a basal value of 219 +/- 27 pg/ml to 449 +/- 66 pg/ml 60 min postprandial (p < 0.001), and remained elevated until 4 h after food intake. However, no increase was seen from 8 to 12 h in any of the hormones studied, indicating that they are not directly involved in the enhancement of exocrine pancreatic secretion during this period.

Postprandial modifications of plasma secretin levels during pancreatic secretion in dogs

In dogs with a direct pancreatic fistula, a duodenal cannula and a catheter in a saphenous vein, plasma secretin levels, changes in the flow, bicarbonate and chloride concentrations of the exocrine pancreatic secretion as well as in the pH of intraduodenal content have been studied 12 hours after the ingestion of a standard diet. Under these conditions the pancreatic secretion showed a biphasic response with a maximum flow and bicarbonate concentration during the 0-4 and 8-12 h postprandial periods. This coincided with a marked decrease of pH in the intraduodenal content, with values close to 4.5. On the other hand, during the first postprandial hour, plasma secretin values increased from basal ones (218.66 +/- 27 pg/ml) to 448.94 +/- 66 pg/ml, remaining elevated for four hours after the meal ingestion. However, no increase occurred between 8-12 h when intraduodenal pH reached values below 4.5. This study indicated that: 1) plasma secretin levels increased significantly (P less than 0.05) after the ingestion of a standard solid diet, and 2) determinants liberating secretin were not only the presence of a duodenal pH below 4.5, but probably the presence of some macronutrients from the meal.

Pancreatic secretory response to ordinary meals: studies with pure pancreatic juice

We have studied the pancreatic secretory response to a normal meal in 5 subjects with an external drainage of the main pancreatic duct carried out after biliary tract surgery. Pancreatic juice was collected at 60-min intervals from 10 AM to 7 PM, starting 2 h before and ending 7 h after lunch, and was analyzed for volume, bicarbonate content, and protein content. Large doses of pancreatic extract were given between and during meals. Both bicarbonate and protein output increased rapidly after the beginning of the meal and the increase persisted, with minor fluctuations, for the entire 7-h study period between lunch and dinner. The peak postprandial bicarbonate and protein outputs were higher (on average by 20% and 26%, respectively) than bicarbonate and protein outputs induced by exogenous infusion of submaximal doses of secretin and cerulein. The profile and magnitude of the bicarbonate secretory pattern elicited by food were not substantially different from those of protein secretion. In an additional patient who had undergone a duodenocephalopancreatectomy plus two-thirds distal gastrectomy before the study, the pancreatic response to meals showed an initial phase characterized by an increase in pancreatic secretion during the first postprandial hour followed by a tendency to decrease in the subsequent 2 h, and a later phase (from the fourth postprandial hour to the end of the study) characterized by a more marked and more persistent increase in pancreatic secretion than occurred in the initial 3 h. These data indicate that (a) the pancreatic secretory response to ordinary meals is much more prolonged than is generally believed. The late phase of the response is not dependent on gastric emptying of food into the duodenum, but is probably related to the arrival of chyme in the distal ileum. (b) The pancreatic secretory response to a normal meal is quantitatively slightly higher than that produced by exogenous pancreatic stimulation with submaximal doses of secretin and cerulein. (c) The pattern of postprandial bicarbonate secretion is similar to that for protein.

Raised serum concentrations of pancreatic enzymes in cigarette smokers

Circulating concentrations of digestive enzymes, certain lysosomal hydrolases and protease inhibitors were measured in 19 heavy smokers and 13 non-smokers before (basal) and at 15, 30, and 60 minutes after a single intravenous injection of secretin (75 CU). In smokers, basal serum amylase and immunoreactive pancreatic elastase 2 (IRE2) concentrations were about 100% and 25% higher respectively, than in the non-smokers, whereas, no differences were observed in basal immunoreactive cationic trypsinogen (IRCT) concentrations and in acid phosphatase and beta-glucuronidase activities between the two groups. Furthermore, a single injection of secretin to cigarette smokers significantly increased serum amylase, IRCT and IRE2 by 155%, 200%, and 100%, respectively when compared with their corresponding basal levels. No such increment was observed in the non-smokers. In addition, there were no significant differences in serum trypsin or elastase inhibitory capacity or immunoreactive alpha 1-protease inhibitor and alpha 2-macroglobulin levels between smokers and non-smokers. The levels and inhibitory capacity of these protease inhibitors was also not affected by secretin injection. These data suggest that cigarette smoking enhances the responsiveness of the exocrine pancreas to a physiological stimulus such as secretin, with resultant substantial increase in the concentrations of pancreatic hydrolases in blood.

Stimulation of exocrine pancreatic secretion by met-enkephalin

The effect of met-enkephalin on pure exocrine pancreatic secretion was studied in five subjects with external transduodenal drainage of the main pancreatic duct carried out after biliary tract surgery. Intravenous infusion of a low dose of met-enkephalin (0.15 micrograms/kg/h) during submaximal pancreatic stimulation with secretin (25 ng/kg/h) and cerulein (10 ng/kg/h) significantly increased pancreatic outputs. Bicarbonate secretion increased 50% above control values, a more marked effect than the increase in enzyme secretion (maximal rise averaged 22%). The effect of the peptide was rapid, persisted for the duration of met-enkephalin infusion and then tended gradually to diminish.