Age-related stimulation by tetragastrin of gastric mucin biosynthesis in rat

The effects of tetragastrin on gastric mucin biosynthesis in middle-aged ra ts were compared with those in young rats. The incorporation of [H-3]glucos amine and [S-35]sulfate into mucin was stimulated by tetragastrin in cultur ed corpus mucosa from 7-week-old rats, In contrast, tetragastrin could not enhance mucin biosynthesis in stomachs from 52-week-old rats. The isosorbid e dinitrate-induced stimulation of corpus mucin biosynthesis observed in mi ddle-aged rats was essentially the same as that seen in young rats. Nitric oxide (NO) synthase activity of the corpus was significantly reduced in the middle-aged rats compared to the young rats. NO synthase-immunoreactivity was observed at surface mucous cells in the corpus mucosa of young, but not of middle-aged, rats. These results suggest that aging decreases the effec t of gastrin on gastric mucin biosynthesis through the age-related loss of NO synthase function in the surface mucous cell layer of rat stomach. (C) 1 999 Elsevier Science B.V. All rights reserved.