EPITHELIAL-CELL PROLIFERATION AND BIODISTRIBUTION OF RADIOLABELED UROGASTRONE IN THE GASTROINTESTINAL MUCOSA OF YOUNG AND OLD MICE

We have evaluated epithelial cell proliferation and biodistribution of radiolabeled recombinant human urogastrone/epidermal growth factor (I -125 rhUG/EGF) in the gastrointestinal mucosa of young (2+ months) and old (30+ months) mice. Animals were injected intraperitoneally with t he metaphase arrest agent vincristine sulfate and intravenously with I -125 rhUG/EGF. Animals were killed after two hours. Crypt cell product ion rate and uptake of radiolabeled urogastrone were measured in the s ame intestinal tissues. The results demonstrated that older animals ha d significantly greater crypt cell production rate as compared to youn g. However, the uptake of I-125 rhUG/EGF was not significantly differe nt (except in duodenum, where the uptake of I-125 rhUG/EGF was signifi cantly greater in young compared to old animals) between young and old animals. This suggests that increased epithelial cell proliferation i n the aging animals is not associated with increased uptake of I-125 r hUG/EGF. Thus epidermal growth factor/urogastrone may not be a primary factor for the intestinal kinetic differences which exist between you ng and old animals.