Expression of receptors regulating gastric acidity in the developing sheepstomach

Acid secretion first appears in the stomach during the later stages of feta l development. Gastric acid secretion is regulated by the stimulatory effec ts of gastrin, histamine, acetylcholine and the inhibitory actions of somat ostatin on their respective receptors. A semi-quantitative reverse transcri ptase-polymerase chain reaction method for the determination of changes in mRNA expression for these receptors was developed and correlated with known changes in gastric acidity. Glyceraldehyde-3-phosphate dehydrogenase (GAP- DH) was used as a reference and an internal standard. The antrum and fundus from four age groups were assayed: 80 days of gestation, 110 days of gesta tion, term (145 days) and adult animals. The CCK B/gastrin and the histamin e (H-2) receptor mRNA were significantly lower in samples from the fundus o f fetuses. from 80 and 110 days of gestation when compared with the adult f undus. Histamine receptor mRNA in the antrum was also significantly lower i n the 80 and 110 days of gestation samples relative to the term fetal antru m. Somatostatin II receptor mRNA levels in the antrum decreased with increa sing age with no change in the fundus. These findings suggest that changes in receptor gene expression, may be responsible for the diminished gastric acidity and responsiveness observed in the fetal stomach. (C) 2001 Elsevier Science B.V. All rights reserved.