MODULATION OF COLONIC ABERRANT CRYPT FOCI AND PROLIFERATIVE INDEXES IN COLON AND PROSTATE-GLANDS OF RATS BY VITAMIN-E

The effect of a high vitamin E diet on the early stages of colon carci nogenesis and on the proliferative indexes in the colon and in the pro state glands was investigated in rats. F344 male rats were injected wi th azoxymethane (AOM, 15 mg/kg sc). One week later, animals were rando mly allocated into two dietary groups (n = 8 rats/group) normal vitami n E (50 IU/kg diet) and high vitamin E (200 IU/kg diet). The basal die t was the AIN-76 diet modified to contain high corn oil (23% wt/wt). A fter eight weeks of feeding, concentrations of vitamin E in plasma, li ver, and prostate were analyzed. Enumeration of aberrant crypt foci (A CF) in colons and proliferative indexes of colons and prostate glands were determined. The total number of ACF and the average number of abe rrant crypts (AC) per focus were similar in both dietary groups. ACF w ere classified as small (1-3 crypts/focus), medium (4-6 crypts/focus), or large (greater than or equal to 7 crypts/focus). Only the ACF in t he small category showed a significant treatment effect, with values b eing lower in the high vitamin E group than in the control group (p le ss than or equal to 0.05). No significant difference was observed in c olonic proliferative indexes assessed by enumeration of metaphase cell s, S phase cells, or cells exhibiting proliferative cell nuclear antig en (PCNA). The PCNA labeling index in the prostate glands and the acti vity of prostatic acid phosphatase in plasma were higher in high vitam in E-fed rats (p less than or equal to 0.05) than in control animals. The present study demonstrates that additional vitamin E does not inhi bit the induction and growth of ACF; also it enhances the proliferativ e status of the prostate glands.