AJP - Gastrointestinal and Liver Physiology, Vol 257, Issue 3 328-G333, Copyright © 1989 by American Physiological Society
Inhibition of antral gastrin cells by peptide histidine isoleucine
M. M. Wolfe, M. E. Mailliard, B. M. Dunn, E. P. Green and P. S. Karnik
Harvard Digestive Diseases Center, Harvard-Thorndike Laboratory, Boston, Massachusetts.
The present studies were directed to determine whether peptide histidine
isoleucine (PHI), like its structural analogues secretin and gastric
inhibitory peptide, inhibits antral gastrin. In separate experiments, the
effects of PHI on medium gastrin concentrations, the incorporation of
[35S]methionine into newly synthesized gastrin, and steady-state gastrin
mRNA were determined. The inclusion of PHI in the incubation medium
decreased medium gastrin levels at all concentrations examined, an effect
that was not altered by the addition of 10(-6) M tetrodotoxin to the
medium. PHI also inhibited the incorporation of [35S]methionine into newly
synthesized gastrin in a concentration-dependent manner. Steady-state
levels of gastrin mRNA were determined by dot-blot hybridization, using a
32P-labeled gastrin cRNA probe. PHI inhibited gastrin mRNA levels in a
concentration-dependent manner; in contrast, no effect on the levels of
actin and ubiquitin mRNA could be detected, indicating specificity of PHI
on gastrin mRNA. The results of these studies indicate that PHI may exert a
physiological inhibitory effect on antral gastrin cells and that this
inhibition may occur at several steps along the biosynthetic pathway.
