Acid and gastrin responses during intragastric titration in normal subjects and duodenal ulcer patients with G-cell hyperfunction

Effect of Helicobacter pylori on gastric somatostatin in duodenal ulcer disease

Infection of the gastric antrum by Helicobacter pylori is associated with recurrent duodenal ulcer disease but the mechanism of ulcerogenesis is unclear. Since pathways inhibiting gastric secretion are defective in patients with duodenal ulcers, we investigated whether H pylori interferes with the normal gastric inhibition that is mediated by somatostatin. We studied 28 patients with active duodenal ulcers in whom H pylori was eradicated successfully. In 18 patients, we measured the density of antral somatostatin-immunoreactive cells and in a further 10 subjects, the amount of somatostatin mRNA before and after eradication of H pylori was determined. After eradication, the median density of somatostatin-immunoreactive cells increased significantly from 9 (range 3-47) to 19 (6-57) cells per mm muscularis mucosa (p = 0.025). The median somatostatin mRNA/rRNA ratio increased from 50 (25-160) to 95 (40-180) (p = 0.01). The number of gastrin cells and quantity of gastrin mRNA did not change significantly. Our results suggest that in duodenal ulcer disease, gastric secretory function is disinhibited through the suppression of mucosal somatostatin.

Suppression of Helicobacter pylori reduces gastrin releasing peptide stimulated gastrin release in duodenal ulcer patients

Helicobacter pylori increases gastrin release in duodenal ulcer patients. This may be through disruption or changes in the mucus layer affecting the access of luminal stimulants to gastrin releasing cells. The effect of suppressing H pylori on gastrin release stimulated by a non-luminal stimulus, gastrin releasing peptide (GRP), was examined. Eleven patients with active duodenal ulcer disease and colonised with H pylori received an intravenous infusion of GRP (2.9 pmol/kg/minute for 30 minutes) and the plasma gastrin response was measured. Basal and peak pentagastrin stimulated acid output were also determined. Patients were treated with tripotassium dicitratobismuthate (De-Nol) and metronidazole to suppress H pylori and the tests were repeated. Suppression of H pylori decreased plasma gastrin concentrations during GRP infusion, but acid output was not affected. Chromatographic analysis of the forms of gastrin in plasma showed a significant fall in gastrin 17, the predominant form found in the gastric antrum. Gastrin 34 did not fall significantly. This study shows that suppression of H pylori decreases the hypergastrinaemia caused by the nonluminal stimulant, GRP, mainly via decreasing gastrin 17.

Gastrin and somatostatin cells in dyspeptic patients with and without duodenal ulcer: a quantitative study based on multiple biopsy specimens

The numbers of immunoreactive gastrin and somatostatin cells in gastric and duodenal mucosal biopsy specimens from dyspeptic patients with duodenal ulcers and dyspeptic controls without ulcers were calculated using a morphometric method. The levels of gastrin and somatostatin in the tissue were also measured by the radioimmunoassay. The results showed no significant difference in the number of G cells and the level of gastrin in the tissue between the ulcer and non-ulcer groups. However, the number of D cells and the level of somatostatin in the tissue in ulcer patients were remarkably reduced in comparison with those in non-ulcer patients (P less than 0.01 and P less than 0.05, respectively). The G:D cells and gastrin:somatostatin ratios in ulcer patients were much higher than those in the non-ulcer control group. It is considered that the reduction of D cells and the relative lack of somatostatin in duodenal ulcer patients might have a role in the mechanism of the duodenal ulceration.