Gastric argyrophil (enterochromaffin-like), gastrin, and somatostatin cells after proximal selective vagotomy in man

The gastric mucosa 25 years after proximal gastric vagotomy

OBJECTIVE

Vagotomy causes inhibition of basal and post-prandial acid secretion in humans, but the knowledge about the trophic effect of the vagal nerves is limited. Vagotomy is known to induce hypergastrinemia and we aimed to study the long-term effects of proximal gastric vagotomy (PGV) on the oxyntic mucosa and the enterochromaffin-like (ECL) cell density in particular.

MATERIAL AND METHODS

Eleven patients operated with PGV because of duodenal ulcer and age- and sex-matched controls were examined 26 to 29 years postoperatively by gastroscopy with biopsies from the antrum and oxyntic mucosa. Neuroendocrine cell volume densities were calculated after immunohistochemical labeling of gastrin, the general neuroendocrine cell marker chromogranin A (CgA) and the ECL cell marker vesicular monoamine transporter 2 (VMAT2). Gastritis was graded and Helicobacter pylori (H. pylori) status was determined by polymerase chain reaction of gastric biopsies. Fasting serum gastrin and CgA were measured.

RESULTS

Serum gastrin was higher in the PGV group compared to controls (median 21.0 [interquartile range (IQR) = 22.0] pmol/L vs 13.0 [IQR = 4.0] pmol/L, p = 0.04). However, there was neither a significant difference in serum CgA or in CgA (neuroendocrine) nor VMAT2 (ECL cell) immunoreactive cell volume density in the oxyntic mucosa. There was significantly more inflammation and atrophy in H. pylori-positive patients, but PGV did not influence the grade of gastritis.

CONCLUSION

Despite higher serum gastrin concentrations, patients operated with PGV did not have higher ECL cell mass or serum CgA. Vagotomy may prevent the development of ECL cell hyperplasia caused by a moderate hypergastrinemia.

Effect of chronic hypergastrinemia on human enterochromaffin-like cells: insights from patients with sporadic gastrinomas

BACKGROUND & AIMS

The effect of chronic hypergastrinemia alone on gastric enterochromaffin-like (ECL) cells in humans is largely unknown because in the common chronic hypergastrinemic states (atrophic gastritis, chronic proton pump inhibitor use), it is not possible to separate the effect of hypergastrinemia and other factors, such as gastritis or atrophy. Studies of patients with sporadic Zollinger-Ellison syndrome (ZES) allow this separation.

METHODS

In 106 patients with ZES, gastric biopsies were taken, and the qualitative ECL cell pattern/grade and the alpha-subunit of human chorionic gonadotropin (alpha-hCG) expression were determined.

RESULTS

In patients with active disease, 99% had ECL hyperplasia and abnormal alpha-hCG staining. Fifty percent had advanced changes in both of these, with 7% having dysplasia and 0% having carcinoids. Advanced ECL cell and alpha-hCG changes were most affected by the level of hypergastrinemia. For ECL cell changes, even mild hypergastrinemia had an effect. Advanced ECL change was also affected by the duration of drug treatment, cure status, and presence of atrophic gastritis, but not by sex or previous vagotomy. The alpha-hCG expression independently predicted dysplasia.

CONCLUSIONS

In humans, chronic hypergastrinemia alone causes advanced ECL cell change and abnormal expression of mucosal alpha-hCG. No threshold for this effect was detected, as reported by some, and in contrast to animal studies, sex and vagal tone did not play a major role. The long-term risk of developing gastric carcinoids with chronic hypergastrinemia is low in patients with sporadic gastrinomas (at least 100 times less than in patients with multiple endocrine neoplasia type 1 with ZES) for at least 15-20 years.

Neuroendocrine peptide levels in the gastrointestinal tract of mice after unilateral cervical vagotomy

The effects of left and right unilateral cervical vagotomy on the content of several neuroendocrine peptides were studied in different parts of the murine gastrointestinal tract, known to receive vagal innervation. The neuroendocrine peptides investigated were secretin, gastric inhibitory peptide (GIP), gastrin, motilin, peptide YY (PYY), somatostatin, substance P, VIP, neurotensin, neuropeptide Y (NPY), and galanin. The neuroendocrine peptide concentration was affected after both left and right vagotomy, and that the changes in the concentrations of the neuroendocrine peptide levels occurred in all the gastrointestinal segments investigated, namely antrum, small and large intestine. However, these changes varied, depending on which side was vagotomized and the interval after vagotomy. It is concluded that the vagus nerve had an important impact on the neuroendocrine system in the murine gut. It is suggested, furthermore that the contradictory results obtained earlier on the effect of vagotomy on the gastrointestinal peptides may depend on differences in the vagotomy methods used and on differences in observation time after vagotomy.

The effect of vagotomy on enterochromaffin-like cells in Mastomys natalensis

The effect of vagotomy on the development of ECL cell tumours was analyzed during drug-induced hypergastrinemia in Mastomys natalensis, a rodent prone to develop ECL cell tumours. Untreated animals were compared with animals receiving the histamine2-receptor blocker loxtidine (LOX) and with animals subjected to unilateral subdiaphragmatic vagotomy prior to loxtidine treatment (VAG+LOX). Loxtidine (2g/l) was administered in drinking water for 48 weeks to allow multiple ECL cell carcinoids to develop. Plasma gastrin levels were increased in LOX animals (94 +/- 31 pmol/l) and in VAG+LOX animals (181 +/- 59 pmol/l) compared to controls (45 +/- 4 pmol/l). Corpus weight and oxyntic mucosal thickness was almost doubled in all loxtidine-treated animals and the density of mucosal endocrine cells was increased by 65% in the LOX group and by 135% in VAG+LOX animals. No significant differences in mucosal thickness and endocrine cell density were seen when denervated and intact parts of the stomach were compared. In the VAG+LOX animals endocrine cell neoplasia was seen in 60% and dysplasia in 40% of animals compared to 40% neoplasia, 45% dysplasia and 15% hyperplasia in LOX animals. The frequency of neoplastic and dysplastic lesions did not differ between denervated and intact parts of the stomach. Untreated animals showed no neoplastic or dysplastic lesions. It is concluded that unilateral vagotomy has no protective effect on the development of ECL-cell tumours in Mastomys during hypergastrinemia, as opposed to previous studies in the rat.