Effects of longterm epidermal growth factor treatment on the normal rat colon

Background-Epidermal growth factor (EGF) exerts trophic effects on the mucosa of damaged and defunctioned colon, but the effects on the normal large bowel wall are not known. Aims-To investigate the effect of systemic EGF treatment on growth and morphology of normal rat colon. Methods-Rats were treated with subcutaneous biosynthetic EGF injections of 150 mu g/kg/day for 28 days. The weight of the histological colonic wall layers and the luminal surface area were measured using quantitative morphometric analysis (stereology). The colon was subdivided into proximal and distal parts. Results-EGF treatment increased the total colon wet weight by 23% compared with controls (p<0.005). The weight increase occurred in the mucosal (33%) and the submucosal layers of the bowel wall (36%) and there was a 69% increase of the total luminal surface area (p=0.001). In the proximal part of colon of EGF rats there was a 68% increase in mucosal weight (p<0.005) accompanied by a 79% increase in the mucosal surface area compared with controls (p<0.005), whereas submucosal and muscularis propria weights were identical. In distal colon, the mucosal weight increased 28% in the EGF group (p<0.005), the mucosal surface area increased by 72% after treatment (p<0.01). Furthermore there was a 34% increase in the weight of submucosa (p<0.001) in the distal colon among EGF rats. Conclusions-Treatment of rats with EGF has a stimulating role on the mucosa and luminal surface area of the entire functioning colon and a trophic effect on the submucosa of the distal colon.