EXPRESSION OF THE CHROMOGRANIN A-DERIVED PEPTIDES PANCREASTATIN AND WE14 IN RAT STOMACH ECL CELLS

The ECL cells constitute the predominant endocrine cell population in the mucosa of the acid-secreting part of the stomach (fundus). They ar e rich in chromogranin A (CGA), histamine and histidine decarboxylase (HDC). They secrete CGA-derived peptides and histamine in response to gastrin. The objective of this investigation was to examine the expres sion of pancreastatin (rat CGA(266-314)) and WE14 (rat CGA(343-356)) i n rat stomach ECL cells. The distribution and cellular localisation of pancreastatin-and WE14-like immunoreactivities (LI) were analysed by radioimmunoassay and immunohistochemistry with antibodies against panc reastatin, WE,, and HDC. The effect of food deprivation on circulating pancreastatin-LI was examined in intact rats and after gastrectomy or fundectomy. Rats received gastrin-17 (5 nmol/kg/h) by continuous intr avenous infusion ol omeprazole (400 mu mol/kg) once daily by the oral route, to induce hypergastrinemia. CGA-derived peptides in the ECL cel ls were characterised by gel permeation chromatography. The expression of CGA mRNA was examined by Northern blot analysis. Among all of the endocrine cells in the body, the ECL cell population was the richest i n pancreastatin-LI, containing 20-25% of the total body content. Food deprivation and/or surgical removal of the ECL cells lowered the level of pancreastatin-LI in serum by about 80%. Activation of the ECL cell s by gastrin infusion or omeprazole treatment raised the serum level o f pancreastatin-LI, lowered the concentrations of pancreastatin-and WE 14-LI in the ECL cells and increased the CGA mRNA concentration. Chrom atographic analysis of the various CGA immunoreactive components in th e ECL cells of normal and hypergastrinemic rats suggested that these c ells respond to gastrin with a preferential release of the low-molecul ar-mass forms. (C) 1997 Elsevier Science B.V.