THE MASTOMYS GASTRIC CARCINOID - ASPECTS OF ENTEROCHROMAFFIN-LIKE CELL-FUNCTION

The mastomys rodent exhibits a genetic propensity to develop gastric carcinoid tumors. Utilizing acid inhibitory pharmacotherapy (histamine-2 receptor antagonists and proton pump inhibitors), we have demonstrated transformation from normal to neoplastic enterochromaffin-like (ECL) cells in a well-defined fashion over a period of 4 months. In addition, we have demonstrated inhibition of tumor growth with either somatostatin or histamine-1 receptor antagonists (terfenadine and cyproheptadine). In order to define the regulation of growth and secretion of transformed ECL cells, we developed an isolated pure ECL cell system. ECL cells secrete histamine in response to gastrinergic (gastrin), muscarinic (carbachol), and a-adrenergic (isoproterenol) stimulation. Both cAMP and intracellular calcium-dependent mechanisms are involved in the process of histamine secretion.