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  • 1
    Electronic Resource
    Electronic Resource
    Ultrastructure of enterochromaffin-like cells in rat stomach: effects of α-fluoromethylhistidine-evoked histamine depletion and hypergastrinemia (1996)
    Springer
    Cell & tissue research 283 (1996), S. 469-478 
    Details
    ISSN: 1432-0878
    Keywords: Key words: Stomach ; Enterochromaffin-like cells ; Histamine ; α-Fluoromethylhistidine ; Hypergastrinemia ; Rat (Sprague Dawley)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. Histamine-producing enterochromaffin-like (ECL) cells are numerous in the oxyntic mucosa of the rat stomach. They respond to gastrin by secretory activation, hypertrophy and hyperplasia. They contain cytoplasmic granules (median profile diameter 120 nm), secretory vesicles (180 nm) and microvesicles (70 nm). α-Fluoromethylhistidine (α-FMH) depletes histamine from the ECL cells by inhibiting the histamine-forming enzyme histidine decarboxylase. Long-term hypergastrinemia, evoked by omeprazole, increases the ECL-cell histamine concentration. The way in which chronic histamine depletion affects omeprazole-induced ECL-cell hypertrophy, and the ways in which granules and vesicles in the ECL cells respond to α-FMH and/or omeprazole have been studied. Rats were treated with α-FMH (3 mg/kg per h subcutaneously), omeprazole (400 μmol/kg per day orally), α-FMH+omeprazole, or vehicle for 6 weeks. ECL cell profiles in electron micrographs were analysed panimetrically. The results show that the omeprazole-evoked hypertrophy of the ECL cells is not affected by depletion of ECL-cell histamine, thereby supporting the view that ECL-cell histamine is not important for full expression of the gastrin-evoked trophic effects on the ECL cells. The loss of ECL-cell histamine following treatment with α-FMH and with α-FMH+omeprazole is associated with a greatly reduced size of the secretory vesicle compartment. The granules, on the other hand, are unaffected by α-FMH and α-FMH+omeprazole. Omeprazole treatment leads to the appearance of numerous vacuoles (with profile diameter greater than 500 nm); such vacuoles are not observed in the ECL cells of rats treated with α-FMH or α-FMH+omeprazole. The omeprazole-induced increase in ECL-cell histamine is associated with an increase in the compartment composed of secretory vesicles and vacuoles. The findings support the hypothesis that secretory vesicles (and vacuoles) represent a major storage site of ECL-cell histamine.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410050558
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  • 2
    Electronic Resource
    Electronic Resource
    Effect of α-fluoromethylhistidine-evoked histamine depletion on ultrastructure of endocrine cells in acid-producing mucosa of stomach in mouse, rat and hamster (1996)
    Springer
    Cell & tissue research 286 (1996), S. 375-384 
    Details
    ISSN: 1432-0878
    Keywords: Key words: Endocrine cells ; Stomach-ECL cells ; Ultrastructure ; Histamine ; α-Fluoromethylhistidine ; Secretory vesicles ; Rat (Sprague Dawley) ; Mouse (NMRI) ; Hamster (Syrian)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. The oxyntic mucosa of the mammalian stomach is rich in endocrine cells, such as ECL cells, A-like cells, somatostatin cells, D1/P cells and, in some species, enterochromaffin cells. The various endocrine cell types can be distinguished on the basis of their characteristic cytoplasmic granules and vesicles. The ECL cells contain numerous large secretory vesicles and relatively few, small electron-dense granules and small clear microvesicles. We have suggested that in the rat the ECL cells contain most of the gastric histamine with the secretory vesicles as the major histamine storage site in these cells. α-Fluoromethylhistidine is an irreversible inhibitor of histidine decarboxylase, the histamine-forming enzyme. We have previously shown that this enzyme inhibitor depletes histamine from the ECL cells in the rat and reduces the number of secretory vesicles in the cytoplasm. In the present study, we have examined whether α-fluoromethylhistidine affects the ECL cells in other species and whether it affects other types of endocrine cells in the oxyntic mucosa of the rat. Mice, rats and hamsters were treated with the inhibitor (3 mg/kg per h) via minipumps subcutaneously for 24 h. This treatment lowered the oxyntic mucosal histamine concentration by 65–90% and the number and volume density of the secretory vesicles by 85–95% in the ECL cells of the three species examined. In contrast, the number and volume density of granules and microvesicles were not greatly affected. No evidence was found for an effect of α-fluoromethylhistidine on A-like cells, somatostatin cells or D1/P cells of the rat stomach, suggesting that, unlike the ECL cells, they do not contain histamine.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410050707
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  • 3
    Electronic Resource
    Electronic Resource
    Enterochromaffin-like cells in the rat stomach: effect of α-fluoromethylhistidine-evoked histamine depletion (1992)
    Springer
    Cell & tissue research 270 (1992), S. 7-13 
    Details
    ISSN: 1432-0878
    Keywords: Histamine ; Stomach ; Endocrine cells ; Enterochromaffin-like (ECL) cell ; Histidine decarboxylase ; α-Fluoromethylhistidine ; Rat (Sprague Dawley)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In the rat, gastric histamine is stored predominantly in the enterochromaffin-like (ECL) cells, which are located basally in the oxyntic mucosa. The functional significance of histamine in the ECL cells is a matter of speculation. In this study the effect of depletion of histamine on the properties and ultrastructure of the ECL cells was examined. Histamine synthesis was inhibited with α-fluoromethylhistidine (3 mg·kg-1·h-1) given via osmotic minipumps over a period of 24 h. The treatment reduced the histidine decarboxylase activity (approximately 20% remaining) and histamine concentration (less than 20% remaining) in the oxyntic mucosa, as well as the intensity of histamine- and chromogranin A-immunostaining in the ECL cells, compared to control rats. The cytoplasmic (secretory) granules/vesicles were greatly reduced in number and size following α-fluoromethylhistidine administration. The histamine immunostaining of the mast cells, which occurs at the mucosal surface and in the submucosa, appeared unaffected. We conclude that ECL cell histamine accounts for at least 80% of the total oxyntic mucosal histamine in the rat and that it represents a more mobile pool than mast cell histamine. The reduction in the number and size of the ECL cell granules/vesicles following histamine depletion is in accord with the idea that they represent the storage site for histamine.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00381874
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