AJP - Gastrointestinal and Liver Physiology, Vol 247, Issue 3 231-G239, Copyright © 1984 by American Physiological Society
Development of sensitivity to cAMP-inducing hormones in the rat stomach
C. Gespach, Y. Cherel and G. Rosselin
Development of cAMP responses to secretin, pancreatic glucagon, and
histamine was measured in gastric glands of fetal (day 20), postnatal (days
1-30), and adult rats (day 65). cAMP stimulation by these hormones was
already detected on day 20 of gestation. cAMP generation showed biphasic
variations during the 1st days of life and at the onset of weaning (day
20). Anticipated weaning at day 14 triggered precocious maturation
(efficacies) of the cAMP-generating systems sensitive to secretin,
glucagon, and histamine without changing the potencies of the hormones.
During development, the general characteristics (potency and
pharmacological or regulatory properties) of the receptor-cAMP systems
studied were comparable with those evidenced in adult rats. At days 5, 20,
and 65, vasoactive intestinal peptide and the peptide having N-terminal
histidine and C-terminal isoleucine amide (PHI) were about 100 times less
potent than secretin (EC50 = 1.5 X 10(-9) M secretin). The histamine action
could be blocked by the competitive H2-receptor antagonist cimetidine
(70-100% inhibition) as well as by the noncompetitive inhibitor
somatostatin (37-62% inhibition). The data indicate that these regulatory
hormones (secretin, glucagon(s), histamine, and somatostatin) might have a
direct effect on gastric glands and may modulate their biological
activities (metabolism, differentiation, proliferation, and exocrine and
endocrine secretions) from the neonatal period in rats. The important
physiological role of weaning on the final maturation of the
cAMP-generating systems in rat gastric glands is underlined.
