EFFECTS OF HYPOCHLORHYDRIA AND HYPERGASTRINEMIA ON STRUCTURE AND FUNCTION OF GASTROINTESTINAL CELLS - A REVIEW AND ANALYSIS

Since hypochlorhydria can induce hypergastrinemia, and gastrin has a t rophic effect on some gastrointestinal cells, states that cause elevat ed plasma gastrin levels are of interest in terms of effects on cell g rowth and function. This article reviews the relationship between gast ric mucosal cells during periods of acid stimulation and inhibition an d analyses the effects of hypochlorhydria and hypergastrinemia on gast ric and colonic cells and tumors. Hypochlorhydria releases the inhibit ory effect of antral gastrin cells, inducing them to release gastrin i n the presence of peptides or amino acids in the gastric lumen or in r esponse to antral distension. Gastrin stimulates the oxyntic mucosa, w hich may lead to hyperplasia of enterochromaffin-like cells, resulting in enterochromaffin-like carcinoid tumors in aged rats and, rarely, i n patients with chronic atrophic gastritis or gastrinomas. In addition to hypergastrinemia, other factors appear to be required for the prog ression of enterochromaffin-like hyperplasia to carcinoids; genetic fa ctors may be involved. Gastrin elevations due to anti-secretory drug t herapy are indirectly proportional to the degree of acid inhibition an d are reversible upon cessation of therapy. The gastrin levels during omeprazole therapy are similar to those caused by gastric vagotomy. Av ailable evidence does not support a relationship between hypergastrine mia and the occurrence or growth of gastric carcinoma or colonic tumor s.