Effect of running training on DMH-induced aberrant crypt foci in rat colon

PURPOSE: We examined the effects of treadmill-running training on the induction of aberrant crypt foci (ACF), which is the first step of colon cancer induction, in the colonic mucosa of rats injected with 1,2-dimethylhydrazine (DMH). METHODS: Four-week-old F344 rats (N = 38) were randomly assigned to training (19 rats) and control (19 rats) groups. After a week, all rats were given DMH (20 mg·kg body weight) once a week for 2 wk. Running training was started at age 7 wk (speed: 10 m·min, 0% grade, 120 min·d, 5 d·wk). After 4 wk of training, the rats were sacrificed and the colon was removed, opened, and counted for ACF with 0.2% methylene blue staining. RESULTS: Running training resulted in lower body- (P < 0.01) and adipose fat weight (P < 0.05). The numbers of ACF and total AC were significantly lower in the running training group than in the control group (P < 0.05). The occurrences of one, three, and five aberrant crypts per focus were also significantly lower in the running training group than in the control group (P < 0.05). The ratios of total AC/ACF did not significantly differ between the running training and control groups. CONCLUSIONS: The results of the present investigation suggest that low-intensity running training inhibits the DMH-induced initiation of colon ACF development.