Effects of exogenous secretin on pancreatic and biliary ductal and sphincteric pressures in man demonstrated by endoscopic manometry and correlation with plasma secretin levels

Comparison of secretin-stimulated magnetic resonance pancreatography and manometry results in patients with suspected sphincter of oddi dysfunction

RATIONALE AND OBJECTIVES

To measure main pancreatic duct diameter (PDD) with magnetic resonance pancreatography (MRP) before and after secretin injection in patients with suspected sphincter of Oddi dysfunction (SOD) and to determine if the diameter change is predictive of sphincter of Oddi manometry (SOM) results.

MATERIALS AND METHODS

We identified all patients during the study period referred for SOM for clinically suspected SOD; patients with an intact sphincter and without contraindication to MRP examination were considered for study entry. Consenting patients underwent MRP, including dynamic imaging of the pancreatic duct after intravenous administration of porcine secretin followed by SOM during endoscopic retrograde cholangiopancreatography. MRP was defined as abnormal when PDD remained increased by > or = 1.0 mm from baseline 15 minutes after secretin injection. SOM was abnormal when basal sphincter pressure (SP) was > or = 40 mm Hg. Mean PDD before and after secretin administration was compared within normal and abnormal SP groups with two-tailed unpaired t-test; the mean difference between baseline and peak PDD and duration of > or = 0.5 mm increase in PDD was compared between groups with two-tailed t-test. P < .05 was considered significant.

RESULTS

Of 70 patients referred for SOM, 30 met all entry criteria, gave consent to participate, and underwent both MRP and SOM. Ten of 30 patients (33%) had normal SP; 20 (67%) were abnormal. PDD increased significantly after secretin injection (normal SP, 1.62 +/- 0.73 to 2.78 +/- 0.77 mm, P < .01; abnormal SP, 1.45 +/- 0.26 to 2.32 +/- 0.75 mm, P < .01). There was no difference between normal and abnormal SP groups in amount of PDD increase (1.15 +/- 0.75 vs. 0.88 +/- 0.72 mm; P = .33) or duration of > or = 0.5 mm increase in PDD (5.28 +/- 8.76 vs. 13.60 +/- 13.00 minutes; P = 0.07).

CONCLUSIONS

In patients with suspected sphincter of Oddi dysfunction, magnetic resonance pancreatography demonstrated PDD increase following secretin injection but did not predict the results of manometry.

Multiple actions of secretin in the human body

The discovery of secretin initiated the field of endocrinology. Over the past century, multiple gastrointestinal functions of secretin have been extensively studied, and it was discovered that the principal function of this peptide in the gastrointestinal system is to facilitate digestion and to provide protection. In view of the late identification of secretin and the secretin receptor in various tissues, including the central nervous system, the pleiotropic functions of secretin have more recently been an area of intense focus. Secretin is a classical hormone, and recent studies clearly showed secretin's involvement in neural and neuroendocrine pathways, although the neuroactivity and neural regulation of its release are yet to be elucidated. This chapter reviews our current understanding of the pleiotropic actions of secretin with a special focus on the hormonal and neural interdependent pathways that mediate these actions.

The sphincter of Oddi: understanding its control and function

The most common functional disorders of the biliary tract and pancreas are associated with disordered motility of the sphincter of Oddi (SO). The SO is a neuromuscular structure located at the junction of the bile and pancreatic ducts with the duodenum. The primary functions of the SO are to regulate the delivery of bile and pancreatic juice into the duodenum, and to prevent the reflux of duodenal contents into the biliary and pancreatic systems. Disordered motility of the SO leads to the common and painful clinical conditions of SO dysfunction and acute pancreatitis. In order to understand normal SO motility, studies have been performed addressing SO function, control of spontaneous SO activity, responses to bioactive agents, SO innervation, and reflexes with other gastrointestinal organs. These studies have led to the current understanding of how the SO functions and may permit the development of targeted therapy for SO dysfunction and acute pancreatitis. This review summarizes the current knowledge regarding the control and regulation of SO motility, highlighting laboratory based and clinical research performed over the last 5 years.

Secretin MRCP and endoscopic pancreatic manometry in the evaluation of sphincter of Oddi function: a comparative pilot study in patients with idiopathic recurrent pancreatitis

BACKGROUND

Sphincter of Oddi dysfunction plays an important etiologic role in idiopathic acute recurrent pancreatitis. Sphincter of Oddi manometry is the most accurate test of sphincter of Oddi function, but it is associated with an increased risk of post-procedure pancreatitis and is non-diagnostic in about a third of cases. Secretin MRCP has a diagnostic efficacy comparable to ERCP, but data on its sensitivity with regard to sphincter of Oddi function are lacking. The aim of this study was to compare secretin MRCP and pancreatic sphincter of Oddi manometry for evaluation of sphincter of Oddi function in patients with idiopathic acute recurrent pancreatitis.

METHODS

Eighteen consecutive patients with idiopathic acute recurrent pancreatitis underwent secretin MRCP and pancreatic sphincter of Oddi manometry/ERCP. Data from 15 patients were suitable for analysis. Fifteen subjects with asymptomatic, non-pancreatic hyperamylasemia matched for age and gender underwent secretin MRCP and served as a control group.

RESULTS

Sphincter of Oddi manometry documented sphincter dysfunction in 6/15 patients (40%) and secretin MRCP, in 4/15 patients (26.7%). Sphincter of Oddi manometry confirmed the presence of elevated basal sphincter of Oddi pressure in two of the 4 patients with abnormal and other forms of sphincter of Oddi dyskinesia in the other two. None of the control subjects had an abnormal secretin MRCP. Secretin MRCP and sphincter of Oddi manometry were concordant in 13/15 patients (86.7%); positive and negative diagnoses for sphincter of Oddi dysfunction agreed in, respectively, 81.8% and 100% (kappa value 0.706).

CONCLUSIONS

Secretin MRCP seems to be a useful noninvasive procedure for investigation of pancreatic sphincter of Oddi function, but evaluation in larger series is needed.

Secretin-stimulated magnetic resonance pancreaticogram to assess pancreatic duct outflow obstruction in evaluation of idiopathic acute recurrent pancreatitis: a pilot study

Magnetic resonance pancreatography is a new modality to visualize the pancreatic duct. Prolonged dilation of the pancreatic duct following secretin administration may suggest obstruction at the level of the pancreatic duct orifice. We describe 10 patients with idiopathic acute recurrent pancreatitis who underwent secretin-stimulated magnetic resonance pancreatography with subsequent endoscopic retrograde pancreatogram with or without manometry. All patients had complete visualization of the main pancreatic duct and no evidence of chronic duct disease. Two patients had pancreas divisum. Three had prolonged dilation of the pancreatic duct on secretin-stimulated magnetic resonance pancreatography and evidence of pancreatic duct outflow obstruction. Four additional patients with pancreatic duct outflow obstruction had normal secretin-stimulated magnetic resonance pancreatography. In conclusion, secretin stimulated magnetic resonance pancreatography provides high quality pancreatic duct images and has high specificity but low sensitivity for diagnosing pancreatic duct outflow obstruction using manometric/clinical criteria.

Biliary sphincter motility after neural isolation of the pancreatoduodenal region in conscious dogs

BACKGROUND

Several neural and hormonal factors are known to affect the motility of the sphincter of Oddi. However, the precise mechanisms of the control of sphincter motility have not been completely explored. We investigated the relationship of canine biliary sphincter motility when it is extrinsically denervated by neural isolation of the pancreatoduodenal region.

METHODS

Interdigestive and postprandial sphincter motility in a denervated pancreatoduodenal segment and effects of cholecystokinin-octapeptide were studied in 7 conscious dogs. Data were compared with those of 7 neurally intact control dogs.

RESULTS

After extrinsic denervation of the pancreatoduodenal region, sphincter motility exerted a cyclic change in concert with the duodenal myoelectric cycles; this change involved short cyclic bursts of motor activity, which gradually increased in intensity. The increase in the cyclic bursts of motor activity was also cyclic and associated with an increase in the plasma motilin concentration. Neural isolation of the pancreatoduodenal region increased sphincter basal pressure and motility index (integral per minute). In the denervated biliary sphincter, the feeding pattern and temporary inhibitory effect of feeding, as seen in controls, were absent, which suggests the role of extrinsic nerves in delivering bile into the duodenum after feeding. In the denervated dogs, cholecystokinin-octapeptide caused excitation of the sphincter activity, instead of relaxation observed in controls.

CONCLUSIONS

Extrinsic innervation to the pancreatoduodenal region has an inhibitory effect on biliary sphincter motility. Abnormalities in extrinsic innervation to the biliary sphincter might increase the resistance of the sphincter to the bile flow and induce bile stagnation.

Secretin induces variable inhibition of motility in different parts of the Australian possum sphincter of Oddi

The sphincter of Oddi (SO) may not function as a single structure. We aimed to determine the response of the proximal and distal segments of the bile duct (BD-SO) and pancreatic duct (PD-SO) components of the SO to secretin, with and without neural blockade with tetrodotoxin (TTX). In anaesthetized Australian possums, separate manometry catheters were placed in the proximal and distal BD-SO or PD-SO segments to record motility. Secretin, 50-1000 ng kg(-1), was administered, followed by TTX, and re-administration of secretin, 500 and 1000 ng kg(-1). Changes in the motility index (MI, frequency x mean amplitude) were determined. Statistical analysis utilized repeated-measures ANOVA. Secretin produced a dose-dependent decrease in MI from the proximal and distal BD-SO and PD-SO (all P < 0.001). The maximum inhibition, at 1000 ng kg(-1), was 21 +/- 4%, 33 +/- 6% and 42 +/- 5% of control (mean +/- SEM), for proximal and distal BD-SO, and distal PD-SO, respectively. The proximal PD-SO MI, however, was inhibited to 62 +/- 6% of control, at 1000 ng kg(-1). TTX enhanced the secretin-induced response to the same level at the four sites (P < 0.02). We conclude that secretin inhibits the motility of the possum SO in a nonuniform manner and is modulated by neural activity.

Sphincter of Oddi manometry. Paradoxical response to secretin but not to CCK in alcoholic patients with no pancreatic disease

CONCLUSION

In chronic alcohol abusers with no pancreatic disease, secretin was found to induce a paradoxical spasmodic response in the sphincter of Oddi (SO) instead of the relaxation observed in controls. Cerulein, on the contrary, had a normal relaxing effect on the SO.

BACKGROUND

We previously reported SO dyskinesia in cases of chronic pancreatitis. Here we investigated whether chronic alcohol consumption may have contributed to the genesis of this dyskinesia.

METHODS

SO and main pancreatic duct pressures were recorded endoscopically with a dual electronic pressure sensor in 27 chronic alcohol abusers and compared with the values obtained in 15 normal controls. These pressures were recorded both in the basal state and after applying hormonal stimulation by injecting either secretin (1 CU/kg) or cerulein (75 ng/kg).

RESULTS

Cerulein relaxed the SO in both the controls and the chronic alcohol abusers, whereas it transiently enhanced the main pancreatic duct (MPD) pressure. Secretin induced a wave of MPD hyperpressure (+15.4 +/- 3.0 mm Hg) in both groups of subjects, but in the alcoholic group, instead of relaxing SO, it significantly enhanced the amplitude of phasic contractions (+32.6 +/- 8.4 mm Hg). The SO basal pressure was also paradoxically enhanced by secretin in the alcoholic patients (28.8 +/- 8.2 vs 10.1 +/- 2.4 mm Hg).

Sphincter of Oddi motility

BACKGROUND

Technical improvement in endoscopic and manometric technique has allowed direct manometry of the human sphincter of Oddi (SO). The aim of the present review is to describe the present status of physiologic and clinical knowledge of the SO, with emphasis on contributions from Danish Gastroenterology.

RESULTS

The SO is a zone with an elevated basal pressure with superimposed phasic contractions. It acts mainly as a resistor in the regulation of bile flow. Neurohormonal regulation influences the motility pattern. The contractions are under the control of slow waves. Clinical subgroups show abnormalcy in SO manometric pattern especially in patients with biliary or pancreatic pain without demonstrable organic substrate. Evidence suggests that endoscopic sphincterotomy may be of benefit in these patients.

The effects of feeding and secretin administration on the pancreaticoduodenal papilla of conscious dogs

The aim of this study was to define the functional role of the pancreaticoduodenal papilla (PDP) in the regulation of pancreatic outflow into the duodenum in response to feeding and secretin administration in conscious dogs. The canine model we developed allowed for measurement of the pancreatic ductal pressure and pancreatic outflow simultaneously in a physiological state without interfering with the flow of pancreatic juice via the intact sphincter of the duodenal papilla. Feeding increased the pancreatic outflow from 2.8 +/- 0.2 to 13.4 +/- 1.3 ml/15 min with a slight increase in the pancreatic ductal pressure from 8.5 +/- 0.6 to 13.7 +/- 1.4 cmH2O. The administration of secretin increased the pancreatic outflow from 2.8 +/- 0.2 to 12.7 +/- 1.0 ml/15 min without increasing the pancreatic ductal pressure. The viscosity of the pancreatic juice increased during exposure to food, but decreased following food intake and secretin administration, after which the PDP seemed to dilate by about 40% of the fasting value. The results suggest that PDP changes its opening to maintain the pancreatic ductal pressure below a certain level, even if pancreatic secretion into the pancreatic duct increases due to food intake and secretin administration.

Distribution of opioidergic, sympathetic and neuropeptide Y-positive nerves in the sphincter of Oddi and biliary tree of the monkey, Macaca fascicularis

The opioidergic, sympathetic and neuropeptide Y-positive innervation of the sphincter of Oddi (common bile duct sphincter and pancreatic duct sphincter), as well as other segments of the extrahepatic biliary tree was studied in the monkey by use of immunohistochemistry. Methionine-enkephalin-positive nerves were seen to innervate the smooth muscle of all portions of the sphincter of Oddi and also local ganglion cells. No methionine-enkephalin-positive nerves could be detected in the common bile duct, pancreatic duct or gallbladder. Tyrosine hydroxylase-positive nerves occurred between smooth muscle bundles and also ran to local ganglion cells as well as along the common bile duct. Neuropeptide Y-positive nerves were observed within smooth muscle of the sphincter of Oddi (all portions), common bile duct, pancreatic duct and gallbladder. No evidence of any differential innervation of the pancreatic duct and common bile duct sphincters could be detected with these markers.

Functional and morphological relationships between the feline main pancreatic and bile duct sphincters

To analyze the relationships between the bile duct and main pancreatic duct sphincters, the resistance to flow through these sphincters was studied simultaneously with perfusion techniques in anesthetized cats. Basal flow resistance was higher in the pancreatic sphincter than in the bile duct sphincter. The pressure in one duct system was not affected by the flow in the other. The muscular activities in the sphincters were usually well coordinated. Distention of the upper biliary tract or the pancreatic duct system reduced the flow resistance in both sphincters. Cholecystokinin-8 (0.01 micrograms), duodenal distention, and sublingual glyceryl trinitrate (0.4 mg) also relaxed both sphincters, whereas secretin in a dose that induced pancreatic secretion had no consistent effect. Morphine increased flow resistance in both systems. These functional studies indicate that the 2 sphincters share smooth muscle fibers at the level where the flow resistances arise, and there are thus no grounds for separate control of the sphincters. There was no evidence of a functionally common sphincter ampulla. The conclusions drawn from the manometric results were supported by morphological findings in this study.

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.