Abstract
It has previously been shown that in the rat nephrectomy is followed by hypergastrinemia, elevated histidine decarboxylase activity, and lowered histamine content in the gastric mucosa; paradoxically this is accompanied by low gastric acid secretion and lack of response to pentagastrin. The present report deals with the morphological changes in the histamine-containing cells, gastrin (G) cells, and the parietal cells after nephrectomy. The number of gastric enterochromaffin, enterochromaffin-like and G cells was assessed by fluorescence histochemistry. In addition, the concentration of 5-HT in the pyloric mucosa and of histamine in the oxyntic mucosa was determined. Under the fluorescence microscope the enterochromaffin-like cells appeared reduced in number (p < 0.001) corresponding with significant lowering of gastric mucosal histamine content (p < 0.01) after nephrectomy. The number of enterochromaffin cells and gastrin cells was not affected, neither was the 5-HT content. The histamine-containing enterochromaffin-like cells, G cells, and parietal cells were further examined by electron microscopy. Analysis of morphometric data from electron micrographs revealed significant changes in the enterochromaffin-like cells and G cells following nephrectomy. The histamine-containing enterochromaffin-like cells of the oxyntic mucosa comprise two major cell populations, the ECL and the A-like cells. Both ECL and Alike cells were increased in size and the number of cytoplasmic granules per unit area was decreased; G cells in the antrum became smaller while the number of cytoplasmic granules per unit area was increased; and the parietal cells showed almost complete loss of canaliculi but numerous vesicles in the cytoplasm. These changes seem to accord with activation of the ECL and Alike cells and deactivation of the parietal and G cells.