AJP - Gastrointestinal and Liver Physiology, Vol 254, Issue 1 87-G92, Copyright © 1988 by American Physiological Society
Development of gastrin synthesis and posttranslational processing mechanisms in rats
L. R. Marino, K. Sugano and T. Yamada
Department of Pediatrics, University of Michigan Medical Center, Ann Arbor 48109.
To examine the ontogeny of gastrin synthesis and posttranslational
processing mechanisms, we utilized region-specific antisera to determine
the factors that regulate the contents of gastrin and its precursors in the
stomachs of developing rats. Gastrin content increased gradually from birth
to a peak at 5 wk of age, after which there was a slight decrease to levels
observed in mature animals. Unlike gastrin, glycine-extended precursors of
gastrin (G-Gly) increased abruptly in the first day of life but thereafter
increased at a steady state. Dexamethasone treatment and early weaning (at
11 days of age) rapidly increased gastrin content, whereas G-Gly content
was decreased. On weaning animals to adult rat chow abruptly at an age (18
days) when the corticosteroid surge associated with the weaning process had
already occurred, evidence for increases in both gastrin and G-Gly content
were observed 7 days later. In contrast, administration of dexamethasone to
18-day-old rats enhanced gastrin content to a greater extent than G-Gly.
These results suggest that the natural surge in corticosteroids associated
with weaning may enhance gastrin amidation activity, whereas the
concomitant dietary changes may exert a stimulatory effect of gastrin
synthesis.
