Stimulation of mucin metabolism in rat gastric mucosa by histamine

We examined the effects of histamine on mucin localized in the different regions and layers of rat gastric mucosa by determining the changes in the content as well as the biosynthetic activity of the mucin. In vivo administration of 0.8 mg/kg of histamine, which could not induce a concomitant gastric acid secretion, caused a significant increase in the mucin content in the corpus mucosa, but not in the antral mucosa. This increase was due to a significant accumulation of the mucin in the mucus gel and surface mucosa of the corpus region, whereas that in the deep mucosa did not significantly change. In the in vitro incubation system of rat gastric mucosa, histamine and dibutyryl cyclic AMP significantly increased [3H]-labeled mucin in the corpus. The histamine-induced acceleration of mucin biosynthesis was suppressed by ranitidine, but not pyrilamine. In the antrum, the biosynthetic activity showed no significant change by histamine. These results suggest that histamine promotes mucin metabolism via histamine H2 receptors in the surface mucosal layer of the corpus.