Epidermal growth factor induces increased mucosal thickness of the small intestine in mouse

Epidermal growth factor (EGF) is known to exert a mitogenic effect in different tissues, including the digestive tract. The aim of the present study was to evaluate whether long-term infusion of EGF causes trophic effects in the gastrointestinal tract of female mice. The animals were infused subcutaneously in the neck with human recombinant EGF in a dose of 10 micrograms/kg/h (1.6 nmol/kg/h) using an osmotic minipump for 1, 3 and 7 days, respectively. Tritiated thymidine was continuously infused intraperitoneally during the same period, except in the 7-day group, where it was infused during the last 3 days. The mucosal thickness was measured microscopically. As a measurement of DNA synthesis, the amount of thymidine retained in the mucosa was registered using a scintillation counter. After 1 day of EGF infusion, the mucosal thickness was increased in the antrum and, after 3 days, in the fundus. In the proximal duodenum, an increased depth of the crypts was seen after 1 day, followed by increased villi height after 3 and 7 days; in the distal duodenum, EGF evoked increased villi height after 3 and 7 days. The height of villi was increased after 7 days in the jejunum and ileum in the EGF-treated animals. The tritium incorporation was increased in the fundus of the stomach and the proximal duodenum in the EGF-treated animals after 3 days, whereas no significant increase in tritiated thymidine incorporation could be detected in the EGF-treated animals after 1 and 7 days compared to the controls. In conclusion, continuous infusion of EGF evoked increased mucosal thickness in the small intestine, while the trophic effects were only of a short duration in the stomach and absent in the colon.