Cell-specific processing of chromogranin A in endocrine cells of the rat stomach

The rat stomach is rich in endocrine cells. The acid-producing (oxyntic) mu cosa contains ECL cells, A-like cells, and somatostatin (D) cells, and the antrum harbours gastrin (G) cells, enterochromaffin (EC) cells and D cells. Although chromogranin A (CgA) occurs in all these cells, its processing ap pears to differ from one cell type to another. Eleven antisera generated to different regions of rat CgA, two antisera generated to a human (h) CgA se quences, and one to a bovine Ib) CgA sequence, respectively, were employed together with antisera directed towards cell-specific markers such as gastr in (G cells), serotonin (EC cells), histidine decarboxylsae (ECL cells) and somatostatin (D cells) to characterize the expression of CgA and CgA-deriv ed peptides in the various endocrine cell populations of the rat stomach. I n the oxyntic mucosa, antisera raised against CgA(291-319) and CGA(316-321) immunostained D cells exclusively, whereas antisera raised against bCgA(82 -91) and CgA(121-128) immunostained A-like cells and D cells. Antisera rais ed against CgA(318-349) and CgA(437-448) immunostained ECL cells and A-like cells, but not D cells. In the antrum, antisera against CgA(291-319) immun ostained D cells, and antisera against CgA(351-356) immunostained G cells. Our observations suggest that each individual endocrine cell type in the ra t stomach generates a unique mixture of CgA-derived peptides, probably refl ecting cell-specific differences in the post-translational processing of Cg A and its peptide products. A panel of antisera that recognize specific dom ains of CgA may help to identify individual endocrine cell populations.