Association of radiolabeled urogastrone binding with regenerating intestinal mucosa and epidermal growth factor/ urogastrone producing organs in rat

In the present study, we have tested the hypothesis that the regeneration of intestinal epithelium is regulated by changes in the uptake of radiolabeled recombinant human urogastrone (¹²⁵I rhUG) in the regenerating mucosa and epidermal growth factor/urogastrone (EGF/URO) producing organs in the rats. Operations were performed on rats to approximate the ileal mucosa to the serosal surface of the cecum. This procedure allows the regeneration of ileal mucosa onto the serosal surface of the cecum. Groups of 5 rats were killed on the 2nd, 4th, 8th and 12th post-operative days. Two hours before autopsy, rats were given 0.5 ml (50 μCi with 30 μgm protein) of ¹²⁵I rhUG intravenously and the following tissues were removed: regenerating mucosa, salivary gland, duodenum, liver and kidney. Results indicated that the uptake of ¹²⁵I rhUG was significantly greater in the salivary gland and duodenum on the 2nd post-operative day which gradually tapered with increasing time after surgery. A similar pattern in the uptake of ¹²⁵I rhUG was also evident in the regenerating mucosa. Further analysis revealed a significant correlation between the uptake of ¹²⁵I rhUG in the salivary gland and duodenum vs rate of epithelialization and uptake of ¹²⁵I rhUG in the regenerative mucosa. These results suggested that the endogenous EGF/URO produced in the salivary gland and duodenum may be a factor in the regulation of intestinal regeneration; however, the mechanism responsible for reflex stimulation of EGF/URO production in these organs is not known.