Eradication of Helicobacter pylori restores the inhibitory effect of cholecystokinin on gastric motility in duodenal ulcer patients.

BACKGROUND: Increased gastric emptying and defective action of endogenous cholecystokinin (CCK), that is known to inhibit this emptying, have been implicated in the pathogenesis of duodenal ulcer (DU). The aim of this double blind study was to assess whether CCK and somatostatin participate in the impairment of gastric motility in active DU patients before and after Helicobacter pylori eradication. METHODS: Tests were undertaken in 10 DU patients without or with elimination of the action of endogenous CCK using loxiglumide, a selective CCK-A receptor antagonist, before and 4 weeks after eradication of H. pylori with 1 week triple therapy that resulted in healing of all DUs tested. The gastric emptying rate after feeding was determined using the 13C-acetate breath test. Before each test, samples of gastric juice were obtained by aspiration using a nasogastric tube for determination of somatostatin using specific radioimmunoassay. RESULTS: Prior to H. pylori eradication gastric emptying half-time was 31 +/- 6 min in placebo-treated DU patients and this emptying rate was not significantly affected in tests after pretreatment with loxiglumide (10 mg/kg i.v.). Following eradication of H. pylori, in tests with placebo gastric emptying half-time was significantly longer (48 +/- 9 min) compared to that prior to H. pylori eradication. Pretreatment with loxiglumide in H. pylori eradicated DU patients significantly enhanced the gastric emptying rate with an emptying half-time of only 33 +/- 4 min. Eradication of H. pylori resulted in a significant increase in somatostatin concentration in gastric juice and loxiglumide significantly reduced this luminal somatostatin in H. pylori-eradicated subjects compared to values before anti-H. pylori therapy. CONCLUSIONS: 1) H. pylori infection in DU patients is accompanied by enhanced gastric emptying and reduction in luminal release of somatostatin; 2) the failure of loxiglumide to affect gastric emptying in H. pylori-infected DU patients might be attributed, at least in part, to the failure of endogenous CCK to control gastric motility due to deficient release of somatostatin; and 3) H. pylori-infected patients appear to exhibit a deficient somatostatin release by endogenous CCK that can be reversed by the eradication of H. pylori indicating that both CCK and somatostatin may contribute to normalization of gastric emptying following H. pylori eradication in DU patients.

Gastric mucosal blood flow and neutrophil activation in aspirin-induced gastric mucosal damage in man.

Gastric and intestinal injury induced by nonsteroidal anti-inflammatory agents (NSAIDs) such as aspirin (ASA) is a common side effect of this class of drugs, but the mechanism by which these drugs act is not fully explained. In this study the effects of 3 days of continuous oral ASA administration (1 g twice daily) to eight healthy male volunteers were studied. To estimate the extent of mucosal damage, gastroscopy was performed before and after 3 days of ASA treatment, during which the mucosal blood flow was measured by means of laser-Doppler flowmetry. Before each endoscopy gastric microbleeding was measured. Since neutrophil activation has recently been suggested to be involved in the pathogenesis of ASA-induced gastric mucosal damage, we examined the influence of ASA treatment on the activation of leukocytes by determining their association with platelets in the blood. Aspirin-induced acute gastric damage reached about 3.5 in the endoscopic Lanza score. Mucosal blood flow increased significantly after ASA treatment, by about 50% in the oxyntic gland area and by 87% in the antral area. Gastric microbleeding rose from about 0.38 ml/day in the intact stomach to about 7.7 ml/day after ASA treatment. The platelet/neutrophil adherence increased significantly in both thrombin-unstimulated and thrombin-stimulated platelets. We conclude that acute 3 days' administration of ASA in man produces well-defined areas of gastric damage accompanied by a significant increase in gastric microbleeding and gastric blood flow and that ASA promotes platelet/neutrophil adhesion that may resemble the neutrophil/endothelium interaction in the gastric mucosa.

Cholecystokinin in the regulation of gastric acid and endocrine pancreatic secretion in humans.

In this study, a selective antagonist of cholecystokinin (CCK)-A receptors, loxiglumide, was used to evaluate the role of CCK in the control of the release of gastrin and pancreatic hormones (insulin, glucagon, pancreatic polypeptide (PP), and somatostatin) after stimulation with exogenous CCK and ingestion of a standard liquid mixed meal in healthy humans. Exogenous CCK-8, which induced a small but significant increase in gastric acid secretion, resulted in dose-dependent increments in plasma PP levels without significant changes in plasma levels of insulin, glucagon, or somatostatin. Pretreatment with loxiglumide resulted in a marked increase in CCK-induced gastric acid secretion and abolished the increments in plasma PP without alteration of plasma insulin, glucagon, or somatostatin levels. Ingestion of the liquid meal resulted in an immediate rise in intragastric pH from basal values of about 2 to pH6 lasting 90-120 min, and this was accompanied by significant increments in plasma gastrin, insulin, glucagon, PP, and somatostatin. Administration of loxiglumide (1200 mg orally) caused a reduction in the postprandial intragastric pH and the two- to three-fold increase in plasma gastrin. Plasma insulin and glucagon levels in tests with loxiglumide tended to increase, probably owing to accelerated gastric emptying, whereas plasma PP and somatostatin were significantly reduced. This study provides evidence that CCK exerts an inhibitory effect on gastric acid secretion and plasma gastrin release as well as a stimulatory influence on the release of PP and somatostatin via CCK-A receptors but does not influence directly insulin or glucagon secretion in man.

Cholecystokinin in the control of gastric acid secretion in humans.

This study was designed to determine the involvement of cholecystokinin (CCK) in the control of gastric acid secretion in men using loxiglumide, a specific CCK-receptor antagonist. Two groups of healthy subjects (A and B) were used: group A for studies of postprandial gastric secretion and group B for studies with exogenous gastric secretagogues. The cephalic phase activated by modified sham feeding (MSF) in group A subjects increased gastric acid secretion to about 36% of pentagastrin maximum, but treatment with loxiglumide in a standard dose (20 mumol/kg i.v. loading dose plus infusion of 20 mumol/kg/h afterwards) failed to affect this secretion. A 5% peptone meal instilled i.g. (to mimic the gastrointestinal phase) greatly enhanced gastric acid secretion and plasma gastrin concentration, but the addition of loxiglumide in a standard dose resulted in a further increase in both gastric acid and plasma gastrin responses to the peptone meal. Plasma somatostatin response to the peptone meal was significantly reduced by loxiglumide. Infusion of cerulein in gradually increasing doses (15-120 pmol/kg/h) and gastrin-releasing peptide (GRP) (25-200 pmol/kg/h) resulted in dose-dependent stimulation of gastric acid secretion, reaching about 35 and 25% of the maximum attained with pentagastrin. When loxiglumide was added the acid responses to cerulein and GRP were further increased by two- to threefold, attaining a peak similar to the pentagastrin maximum. Administration of loxiglumide resulted in a significant increase in plasma gastrin response to GRP, whereas plasma somatostatin was not significantly altered by loxiglumide.(ABSTRACT TRUNCATED AT 250 WORDS)