EFFECT OF EPIDERMAL GROWTH-FACTOR BY DIFFERENT ROUTES OF ADMINISTRATION ON THE SMALL-INTESTINAL MUCOSA OF RATS FED ELEMENTAL DIET

This study was undertaken to investigate the effect of epidermal growt h factor (EGF) on the rat small intestinal mucosa by three different r outes of administration. Four-week-old rats were fed elemental diet fo r 4 weeks and were administered EGF either subcutaneously, intralumina lly or intraperitoneally with mini-osmotic pumps for a week. Intraperi toneal administration of EGF resulted in a significant increase of muc osal wet weight, mucosal content of protein and DNA, villus height, cr ypt depth and crypt cell production rate. Intraluminal or subcutaneous administration of EGF tended to increase those morphological and prol iferative parameters, but did not cause any significant change. We con clude that EGF caused the hyperplasia of the small intestine of rats m aintained on oral elemental diet and that this trophic effect was clea rly shown by the intraperitoneal route of administration, rather than by the intraluminal route. These results suggest that EGF receptors lo cated in the basal portion of crypt cells play a more important role t han those located in the microvillous membrane.