Gastric mucosal somatostatin-like immunoreactivity in peptic ulcer.

Somatostatin (SS) has been reported to exert potent inhibitory effects on gastric acid, pepsin and gastrin secretion. Although still controversial, the results of several studies have shown a possible influence of a local decrease in gastric somatostatin in the physiopathologic characteristics of peptic ulcer disease. In the present study, immunoreactive SS content (SLI) of antral (SLI-a), corpal (SLI-c) and fundic (SLI-f) mucosal extracts was measured by radioimmunoassay (RIA) in control patients (C) and in those patients with duodenal ulcer (DU) or gastric ulcer (GU) to further study a possible role of SS in peptic ulcer disease. Fifty-five patients (C = 20, DU = 21 and GU = 14) were included in the study. Gastric mucosal samples were obtained either by endoscopic biopsy (4.6 +/- 0.2 milligrams of weight) or operation (52.3 +/- 3.8 milligrams of weight). RIA was performed after a modified Arimura's method and results were expressed as nanograms per milligram of tissue plus or minus standard error of the mean. Chromatographic analysis of gastric mucosal extracts was performed on a Sephadex G-25 fine column. A great interindividual variation in SLI levels was observed (a range of 0.02 to 5.30 nanograms per milligram of weight). The mean SLI concentrations were: C (SLI-a, 2.55 +/- 0.45, SLI-c, 0.99 +/- 0.46 and SLI-f, 1.03 +/- 0.21); DU (SLI-a, 0.48 +/- 0.16, SLI-c, 0.43 +/- 0.13, and SLI-f, 0.58 +/- 0.12), and GU (SLI-a, 1.10 +/- 0.25, SLI-c, 0.40 +/- 0.10, and SLI-f, 0.81 +/- 0.24). Significantly greater amounts of SLI contents were found in the antrum of control patients as compared with those found in the corpus or fundus (p less than 0.05 and p less than 0.01, respectively). SLI-a levels were lower in peptic ulcer patients (DU, p less than 0.001 and GU, p less than 0.05) than in control patients. There was also a significant difference between SLI-a levels in DU versus GU patients (p less than 0.05). No significant differences were found in SLI-c and SLI-f contents in all three groups studied. In conclusion, these results suggest that decreased SS levels in antral gastric mucosa could be the alteration underlying the various physiopathologic mechanisms involved in the development of peptic ulcer disease.