Immunochemical characterization of gastrin in pancreatic islets of normal and genetically obese mice.

Material with gastrin-like immunoreactivity has been extracted from micro-dissected islets and from antral mucosa of normal and genetically obese mice. The islet and antral extracts cross-reacted with antisera specific for the CO2H-terminal portion of human heptadecapeptide gastrin, but did not cross-react with antisera specific for the NH2-terminal region or with an antiserum specific for the entire, intact, molecule. With the antiserum showing highest cross- reactivity, the concentration of immunoreactive gastrin in normal islet tissue (138 pmol/g, standard human G17-I) was approximately 50% that in obese mouse islets (204 pmol/g) and 2% that in normal antral mucosa (6-1 nmol/g). Following fractionation on Sephadex G-50 the principal forms of gastrin in the islet and antral extracts had similar elution volumes to human heptadecapeptide gastrin, although other, probably smaller, forms of gastrin were also noted in the islet extracts.