The effect of voluntary exercise on
3'-methyl-4-dimethylaminoazobenzene (3'-Me-DAB)-induced
hepatomas was investigated in male Jc1:Wistar rats. Beginning
at 10 weeks of age, animals were divided into two groups (sedentary and exercise) and housed in individual cages. Food intake and wheel exercise were automatically controlled in the cages of the exercise group.
Body weights were monitored throughout the study. Food availability was controlled in order to equate length and
weight gain. From 27 weeks to termination of the study at 62 weeks, all animals were administered 3'-Me-DAB in the diet at a dose level of 0.0177 g/day/kg body wt. All animals were sacrificed at 62 weeks of age. The incidence of
hepatomas was significantly lower in the exercise group as compared with the sedentary group (0% and 65%, respectively). Liver weight was significantly greater in the exercise group compared with sedentary animals without
hepatomas. The weight of epididymal fat pads was significantly lower in the exercise group. Serum alkaline
phosphate was significantly higher in the exercise group as compared with the sedentary group. Serum
gamma-glutamyl-transpeptidase levels were higher in the sedentary group than in the exercise group. In addition,
gamma-glutamyl-transpeptidase levels were significantly higher in sedentary animals with
hepatomas than in sedentary animals without
hepatomas. These results demonstrate that voluntary exercise decreases 3'-Me-DAB-induced
hepatomas and that this decrease is associated with an increase in serum
alkaline phosphatase and a decrease in serum
gamma-glutamyl-transpeptidase levels.