Effect of secretin on growth of stomach, small intestine, and pancreas of developing rats.

Secretin is present in the intestine of a number of developing species, and plasma secretin levels are elevated in newborn pigs and humans. Secretin stimulates the growth and affects the enzymatic composition of the stomach, small intestine, and pancreas in adult rats. This suggests a possible role for secretin in the rapid postnatal growth of these organs. We investigated this hypothesis by injecting rats subcutaneously with secretin (100 micrograms/kg) every 12 hr for seven days beginning on postnatal day 3, 6, 13, or 24. Growth parameters (weight, content of protein, DNA) as well as the composition of organ-specific enzymes of the stomach, small intestine, and pancreas were measured. Secretin increased growth parameters of the stomach and small intestine in a similar pattern, and in a quantitatively different fashion from that observed in the pancreas. Secretin's effects were also dependent on postnatal age for all organs studied. These data demonstrate that secretin can influence organ growth and enzyme composition of the stomach, small intestine, and pancreas of developing rats and may be one factor regulating growth and development of these organs.