Neuroendocrine (ECL cell) differentiation of spontaneous gastric carcinomas of cotton rats (Sigmodon hispidus)

Background and Purpose: Female inbred cotton rats develop adenocarcinomas i n the oxyntic mucosa, Since a female preponderance is typical for enterochr omaffin-like (ECL) cell tumors, we examined such tumors for ECL cells. Gast rin plays a decisive role in ECL cell tumorigenesis, so blood gastrin conce ntration and gastric mucosal pH were measured. Methods: The stomachs from six female cotton rats (6 to 8 months old) were studied histologically, and at euthanasia, gastric mucosal pH was determine d. Euthanasia was performed on 15 other female cotton rats of similar age f or determination of blood gastrin values by radioimmunoassay (RIA) and gast ric mucosal pH, Rats were classified macroscopically to have normal or thic k oxyntic mucosa, with or without tumor. Results: Among the six cotton rats studied histologically, two 6-month-old rats had normal and two others had thick gastric mucosa, whereas two 8-mont h-old rats had thick. mucosa with tumors. The ECL cells were markedly hyper plastic in all rats with thick mucosa, and ECL cells were found in the neop lastic parenchyma, All cotton rats with normal-appearing gastric mucosa had pH <2.5, whereas 14 rats with thick mucosa had pH >3.1 and hypergastrinemi a, Conclusions: Gastrin may play a major role in ECL cell hyperplasia and, per haps, in adenocarcinoma genesis.