EFFECTS OF HISTAMINE ON MUCIN BIOSYNTHESIS IN RAT GASTRIC-MUCOSA

Mucin biosynthesis is stimulated by gastrin during the process of glyc osylation in the corpus mucosa of the rat stomach. The purpose of this study was to clarify, using an organ culture technique, whether biosy nthetic responses to histamine in the rat gastric mucin are the same a s that to gastrin. Radiolabeled mucin was obtained from the corpus and antral mucosa of the rat stomach after in vitro incubation for 5 h wi th [H-3]glucosamine (GlcN), [C-14]threonine (Thr), and [S-35]sulfate. Addition of histamine (10(-7)-10(-5) M) to the culture medium increase d [H-3]GlcN-labeled mucin in the corpus tissue in a concentration-depe ndent manner. In the antrum, there was no significant change in the bi osynthetic activity of mucin in response to histamine. Histamine at 10 (-5) M also increased the incorporation of both [S-35]sulfate and [C-1 4]Thr into the corpus mucin. These results indicate that histamine sti mulates the biosynthesis of the mucin peptide, as well as the glycosyl ation step in the corpus, and suggest that the effect of histamine on mucin synthesis is distinct from that of gastrin.