ORAL INSULIN-LIKE GROWTH-FACTOR-I STIMULATES INTESTINAL ENZYME MATURATION IN NEWBORN RATS

Insulinlike growth factor-I (IGF-I) has been found in the milk of vari ous species. To investigate if milk-borne IGF-I has any effect on post natal gut development in neonatal animals, newborn rat pups were given orally 1 mu g recombinant human IGF-I daily for 3 days. For compariso n, a separate group of newborn pups was given 150 mu g hydrocortisone, the hormone known to stimulate intestinal maturation in neonatal rats . Oral IGF-I treatment had no significant effect on the animal body we ight nor on the weight of the stomach, small and large intestines, and pancreas. Oral administration of hydrocortisone significantly reduced body weight gain, but it had no apparent effect on internal organ wei ghts. Both IGF-I and hydrocortisone treatments, however, significantly increased lactase, maltase and sucrase activities and hydrocortisone significantly increased aminopeptidase activity at the proximal small intestine when compared with the control. The finding supports the hyp othesis that milk-borne IGF-I may play a role in regulating postnatal gut development in the suckling young.