[Effects of indomethacin and prostaglandin E2 administered intrarectally on colon carcinogenesis induced by azoxymethane (AOM) in rats].

AOM was administered subcutaneously once a week for 11 consecutive weeks to the rat. On the 15th and 30th week after starting of AOM injection, PGE2 content of the colonic mucosa, tumor and blood of portal vein and NK activity of the spleen and mesenteric lymph node (MLN) were evaluated. On the 15th week, a significant high value of the PGE2 content of colonic mucosa was shown when compared with that of the AOM non-administered group (control group). However, no significant difference was observed in the PGE2 content of blood of portal vein and NK activity of the spleen and MLN. On the 30th week, significant high values of the PGE2 content of AOM-induced tumor and blood of portal vein and low values of NK activity of the spleen and MLN were shown when compared with that of the control group. When indomethacin (IND) was administered intrarectally twice a week for 19 consecutive weeks after completion of AOM injection, induced-colon tumors was significantly suppressed. For this reason, it is important to administer IND at the point when the PGE2 content of colonic mucosa begins to augment.