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 prese nt study was to evaluate whether long-term infusion of EGF causes trop hic 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 mu g/kg/h (1.6 nmol/kg/h) using an osmotic minipump for 1 , 3 and 7 days, respectively. Tritiated thymidine was continuously inf used intraperitoneally during the same period, except in the 7-day gro up, 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 scin tillation counter. After 1 day of EGF infusion, the mucosal thickness was increased in the antrum and, after 3 days, in the fundus. In the p roximal duodenum, an increased depth of the crypts was seen after 1 da y, followed by increased villi height after 3 and 7 days; in the dista l 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 ECF-treated animals. The tritium incorporation was increased in t he fundus of the stomach and the proximal duodenum in the EGF-treated animals after 3 days, whereas no significant increase in tritiated thy midine incorporation could be detected in the EGF-treated animals afte r 1 and 7 days compared to the controls. In conclusion, continuous inf usion of EGF evoked increased mucosal thickness in the small intestine , while the trophic effects were only of a short duration in the stoma ch and absent in the colon.