SUPPRESSION OF AZOXYMETHANE-INDUCED RAT COLON ABERRANT CRYPT FOCI BY DIETARY PROTOCATECHUIC ACID

The modifying effect of dietary exposure to protocatechuic acid (PCA) on the development of azoxymethane (AOM)-induced colonic aberrant cryp t foci (ACF) was investigated in male F344 rats. The effects of PCA fe eding on the silver stained nucleolar organizer regions protein (AgNOR s) count in the colonic epithelial cells and on the ornithine decarbox ylase (ODC) activity in the colonic mucosa were also estimated. Animal s were given weekly s.c. injections of AOM (15 mg/kg body weight) for 3 weeks to induce ACF. These rats were fed diet containing 1000 or 200 0 ppm PCA for 5 weeks, starting one week before the first dosing of AO M. All Fats were killed 2 weeks after the last AOM injection, to measu re the number of ACF, ODC activity, and AgNORs count per nucleus in th e colon. In rats given AOM and PCA, the frequency of ACF/colon was sig nificantly decreased compared with that in rats given AOM alone (P < 0 .005 at 1000 and P < 0.05 at 2000 ppm). ODC activity in the colon of r ats given AOM and PCA at both doses was also significantly lower than that of rats treated with AOM alone (P < 0.05). Similarly, the mean Ag NORs count in rats fed PCA was significantly smaller than that of rats treated with AOM alone (P < 0.0001). Treatment with PCA alone did not affect these three biomarkers. These results provide further evidence that PCA could be a chemopreventive agent against rat colon carcinoge nesis.