Epidermal growth factor in human milk and the effects of systemic EGF injection on intestinal calcium transport in suckling rats.

Epidermal growth factor (EGF) is a polypeptide that stimulates proliferation and differentiation of a variety of cell types, including intestinal epithelium; it is the agent in human milk that induces mitosis in human fibroblast culture. It has been postulated that EGF in human milk may play an important role in the normal intestinal maturation since specific EGF receptors are present on the surface of intestinal cells. For this reason, human milk samples from mothers delivering prematurely, as well as at term gestation, were analyzed for their content of EGF. Samples from mothers delivering prematurely showed levels of 70 +/- 5 ng ml-1 and those delivering at term had levels of 68 +/- 19 ng ml-1. There was no diurnal variation and no change with length of lactation up to 50 days. Although previous studies demonstrated that subcutaneous injections of EGF given to suckling rats caused changes in morphology and enzyme activities, no studies had demonstrated that EGF caused changes in function. We injected two-week-old suckling rats and three-week-old weanling rats with 0.1 microgram of g-1 BW twice daily for three days. EGF treatment caused a decrease in somatic weight gain, an increase in weight per unit length of bowel, an increase in lactose specific activity and an increase in net calcium transport. In contrast to the two-week-old suckling rats, the EGF had no effect on intestinal function although somatic weight gain was also depressed in three-week-old animals. These findings demonstrate that human milk contains substantial amounts of EGF and that systemic injections of EGF can cause both morphological and functional changes in the intestinal tract of suckling rats.