EPIDERMAL GROWTH-FACTOR AND THE MATURATION OF INTESTINAL SUCRASE IN SUCKLING RATS

The regulatory effect of epidermal growth factor (EGF) on the postnata l maturation of sucrase was investigated in the small intestine of suc kling and weanling rats. Administration of EGF (0.5 mug . g body wt-1 - day-1) to suckling rats caused a slight precocious induction of sucr ase expression. In weanling rats EGF markedly stimulated sucrase activ ity; however, at both ages, the effect of hydrocortisone was more pote nt. When the glucocorticoid antagonist RU-38486 was administered to su cklings, the precocious induction of sucrase activity by hydrocortison e was inhibited by 80%. However, RU-38486 or adrenalectomy did not pre vent the inductive effect of EGF, indicating that EGF acts in a glucoc orticoid-independent manner. EGF also potentiated the effect of hydroc ortisone and dietary sucrose on the precocious induction of sucrase ac tivity in the sucklings. At weaning, administration of an antiserum sp ecific to rat EGF significantly decreased sucrase activity. This study shows the involvement of EGF in the postnatal maturation of intestina l sucrase in the rat.