Biochemical mechanisms of regulation of gastric secretion of pepsin
Argutinskaia, S.V.; Bersimbaev, R.I.; Ershova, L.P.; Kiseleva, E.V.; Khristoliubova, N.B.
Voprosy Meditsinskoi Khimii 28(1): 92-98
1982
ISSN/ISBN: 0042-8809 PMID: 6278765 Document Number: 194339
Pentagastrin at a dose of 300 .mu.g/200 g of body wt stimulated the secretion of pepsin/pepsinogen. This effect of the hormone was inhibited by actinomycin D and cycloheximide. Histamine and cAMP also elevated the pepsin secretion, but inhibitors of RNA and protein synthesis did not affect these phenomena. As shown by EM of the gastric mucosal main cells and by morphometric analysis, the amount of membranes in the granular endoplasmic reticulum (GER) and the volume of granules containing pepsinogen increased after treatment with pentagastrin. In the presence of histamine and cAMP, GER was unaltered, but the volume and amount of secretory granules in the cytoplasm were decreased. Thus, pentagastrin increased pepsin secretion due to the induction of its synthesis during transcription-translation, while histamine and cAMP only stimulated pepsin production in the main cells. The effect of histamine was inhibited by its antagonist, burimamide, which partly limited the stimulating action of pentagastrin. The effect of pentagastrin on pepsin secretion was partially mediated via histamine. A regulation scheme of the pepsin secretion is presented according to which gastrin has a double mode of action, directly on the main cells with stimulation of the pepsinogen synthesis and indirectly in involving the cascade mechanism of activation of HCl secretion, which stimulates pepsinogen secretion and the corresponding formation of pepsin.