STIMULATION OF MUCUS GLYCOPROTEIN-BIOSYNTHESIS IN RAT GASTRIC-MUCOSA BY GASTRIN

We examined the effects of the gastrin family of peptides on gastric m ucus glycoprotein (mucin) biosynthesis in rat gastric mucosa using an organ culture technique. Radiolabeled mucin was obtained from the tiss ue and culture medium of the corpus and antrum of rat stomach incubate d for 5 hr with [H-3]glucosamine (GlcN), [C-14]threonine (Thr), and [S -35]sulfate in vitro. With the addition of 10(-8) and 10(-7) M tetraga strin to the culture medium, [H-3]GlcN labeled mucin in the corpus tis sue increased to 120-135% that of the control (P < 0.01). The biosynth etic responses to cholecystokinin (CCK)-8 and the 17-peptide gastrin w ere essentially the same as that to tetragastrin. Tetragastrin 10(-8) M also increased the incorporation of [S-35]sulfate into the corpus mu cin but failed to change [C-14]Thr incorporation. In the antrum, biosy nthetic activity showed no significant change with 10(-9) approximatel y 10(-5) M tetragastrin. Ranitidine, diphenhydramine and omeprazole at 10(-5) M did not suppress the tetragastrin-induced increase in [H-3]G lcN incorporation into mucin, but L-365,260 at a concentration of 10(- 6) M completely blocked this effect. These results suggest that gastri n stimulates mucin production via CCK-B/gastrin receptors in the oxynt ic region of rat gastric mucosa.