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 growth factor (EGF) on the rat small intestinal mucosa by three different routes of administration. Four-week-old rats were fed elemental diet for 4 weeks and were administered EGF either subcutaneously, intraluminally or intraperitoneally with mini-osmotic pumps for a week. Intraperitoneal administration of EGF resulted in a significant increase of mucosal wet weight, mucosal content of protein and DNA, villus height, crypt depth and crypt cell production rate. Intraluminal or subcutaneous administration of EGF tended to increase those morphological and proliferative parameters, but did not cause any significant change. We conclude that EGF caused the hyperplasia of the small intestine of rats maintained on oral elemental diet and that this trophic effect was clearly shown by the intraperitoneal route of administration, rather than by the intraluminal route. These results suggest that EGF receptors located in the basal portion of crypt cells play a more important role than those located in the microvillous membrane.