Functional impairment of the individual rat stomach ECL cell in response to sustained hypergastrinemia

ECL cells in the oxyntic mucosa secrete histamine and pancreastatin in response to gastrin. The present study examined gastrin-evoked ECL-cell responses over a 10-week time span in terms of individual ECL cells and unit ECL cell volume. Rats were treated with omeprazole (400 micromol/kg per day orally). The concentrations of gastrin and pancreastatin in serum and of histamine and pancreastatin in the oxyntic mucosa were measured as was the activity of the oxyntic mucosal histidine decarboxylase (HDC). The ECL cells were visualized by immunostaining of histamine and examined by electron microscopy. The total ECL cell number and volume, and the mean ECL cell diameter and volume were determined. The HDC, chromogranin A (CGA) and cholecystokinin-B (CCK-B) receptor mRNA concentrations were determined. In terms of individual ECL cells and unit ECL cell volume, the serum pancreastatin concentration, the oxyntic mucosal histamine content, HDC activity, and HDC, CGA and CCK-B receptor mRNA contents increased slowly at first and then leveled off or started to decline after 2 weeks. After 10 weeks all ECL-cell parameters (expressed per unit ECL cell volume) were back to or approaching the starting value. In conclusion, sustained hypergastrinemia first activates each individual ECL cell (with a peak after 1-2 weeks) and then causes gradual functional impairment, the activity returning towards the pre-stimulation level.