Role of secretin and CCK in the stimulation of pancreatic secretion in conscious dogs. Effects of atropine and somatostatin

Heart Failure and Pancreas Exocrine Insufficiency: Pathophysiological Mechanisms and Clinical Point of View

Heart failure is associated with decreased tissue perfusion and increased venous congestion that may result in organ dysfunction. This dysfunction has been investigated extensively for many organs, but data regarding pancreatic (exocrine) dysfunction are scarce. In the present review we will discuss the available data on the mechanisms of pancreatic damage, how heart failure can lead to exocrine dysfunction, and its clinical consequences. We will show that heart failure causes significant impairment of pancreatic exocrine function, particularly in the elderly, which may exacerbate the clinical syndrome of heart failure. In addition, pancreatic exocrine insufficiency may lead to further deterioration of cardiovascular disease and heart failure, thus constituting a true vicious circle. We aim to provide insight into the pathophysiological mechanisms that constitute this reciprocal relation. Finally, novel treatment options for pancreatic dysfunction in heart failure are discussed.

Changes in duodenal enteroendocrine cells in patients with irritable bowel syndrome following dietary guidance

The densities of enteroendocrine cells are abnormal in patients with irritable bowel syndrome (IBS); however, they tend to change toward normal levels in stomach, ileum, and colon following dietary guidance. The aim was to identify the types of duodenal enteroendocrine cells affected after receiving dietary guidance in the same group of patients with IBS. Fourteen patients with IBS and 14 control subjects were included. The patients received three sessions of dietary guidance. Both groups underwent gastroscopies at baseline, and again for the patients after 3–9 months (median, four months) from receiving dietary guidance. Tissue biopsies were collected from the descending part of the duodenum and were immunostained for all the types of enteroendocrine cells and were then quantified by using computerized image analysis. Using the Kruskal–Wallis non-parametric test with Dunn’s test as a post-test, the results showed a significant difference in the secretin cell densities between control subjects and patients with IBS prior to and following dietary guidance (P = 0.0001 and 0.011, respectively). The corresponding P values for cholecystokinin (CCK) cell densities were 0.03 and 0.42, respectively; gastric inhibitory peptide (GIP) cell densities were 0.06 and 0.43, respectively; serotonin cell densities were <0.0001 and 0.002, respectively; and for somatostatin cell densities were <0.0001 and 0.052, respectively. The Paired t-test showed a significant difference only in the serotonin (P = 0.03) and somatostatin (P < 0.0001) cell densities between IBS patients prior to and following dietary guidance. The changes in the cell densities of secretin, CCK, and GIP were not significant between IBS patients prior to and following dietary guidance. In conclusion, the densities of several duodenal enteroendocrine cells in IBS patients changed toward the values measured in control subjects following dietary guidance. The changes in serotonin and somatostatin cell densities may have contributed to the improvements in IBS symptoms, particularly pain and diarrhea.

A decade of experiences with radioimmunoassays for cholecystokinin in The Netherlands

The radioimmunologic determination of cholecystokinin (CCK) has proved to be notoriously difficult. This is due to the specificity of antibodies, preparation of radiolabeled CCK and low CCK concentrations in human plasma. About 10 years ago we succeeded in developing two highly sensitive region-specific radioimmunoassays for CCK. Antibody T204 binds to the sulfated tyrosine region of CCK, while antibody 1703 reacts with biologically active molecular forms of CCK containing at least 14 amino acid residues. Both antibodies are devoid of significant cross-reaction with gastrin. By means of these two radio-immunoassays CCK concentrations were measured in both tissue and plasma of various species, including man. In addition, the molecular forms of CCK in tissue and plasma were characterized. These CCK assays were used to study the mechanism of CCK secretion. It appeared that digested rather than intact protein and fat stimulated CCK release from the small intestine. The physiologic and pathophysiologic role of CCK in humans was studied using CCK radioimmunoassays and specific CCK-receptor antagonists. CCK was found to play an important role in pancreatic enzyme secretion, gallbladder contraction, and gastrointestinal motility but possibly also in pancreatic carcinogenesis and regulation of satiety and satiation.

Comparison of loxiglumide, a cholecystokinin receptor antagonist, and atropine on hormonal and meal-stimulated pancreatic secretion in man

The effects of loxiglumide, a potent cholecystokinin (CCK)-receptor antagonist, and atropine, a muscarinic receptor blocker, on exocrine pancreatic secretion stimulated by hormones (secretin plus CCK) and a Lundh test meal were studied in healthy young volunteers. Loxiglumide infused intravenously in gradually increasing doses (2-16 mumol/kg-h) caused a dose-dependent inhibition of pancreatic enzyme secretion induced by intravenous infusion of a constant dose of secretin (82 pmol/kg-h) plus CCK-8 (85 pmol/kg-h) but had relatively smaller influence on duodenal volume flow and bicarbonate output. Atropine (20 nmol/kg) also caused a significant reduction in pancreatic enzyme secretion but failed to affect the volume flow or bicarbonate secretion induced by secretin plus CCK, possibly owing to the high doses of secretin and CCK used in these tests. Both loxiglumide and atropine inhibited the pancreatic enzyme response to a Lundh meal, but atropine was more effective in the early phase and loxiglumide in the late phase of the postprandial secretion. Neither loxiglumide nor atropine affected the plasma gastrin and CCK levels, but both antagonists reduced plasma pancreatic polypeptide responses to the Lundh meal. We conclude that 1) loxiglumide results in a relatively stronger suppression of the pancreatic enzyme than aqueous-alkaline secretion induced by secretin plus CCK, whereas atropine inhibits only enzyme secretion; and 2) both loxiglumide and atropine suppress the pancreatic enzyme responses to the meal stimulation without affecting the postprandial plasma gastrin and CCK responses.